Questões - AFA 2018 | Gabarito e resoluções

(AFA - 2018) Quando necessrio, use: - Acelerao da gravidade: g = 10 m/s2; - sen 19 = cos 71 = 0,3; - sen 71 = cos 19 = 0,9; - Velocidade da luz no vcuo: c = 3,0 108m/s; - Constante de Planck: h = 6,6 1034 J s; - 1 eV = 1,6 1019 J; - Potencial eltrico no infinito: zero. COMO A HIPERMETROPIA ACONTECE NA INFNCIA: muito comum bebs e crianas apresentarem algum tipo de erro refrativo, e a hipermetropia o caso mais constante. Isso porque este tipo de ametropia (erro de refrao) pode se manifestar desde a fase de recm-nascido. A hipermetropia um erro de refrao caracterizado pelo modo em que o olho, menor do que o normal, foca a imagem atrs da retina. Consequentemente, isso faz com que a viso de longe seja melhor do que a de perto. (...) De acordo com a Dra. Liana, existem alguns fatores que podem influenciar a incidncia de hipermetropia em crianas, como o ambiente, a etnia e, principalmente, a gentica. As formas leves e moderadas, com at seis dioptrias, so passadas de gerao para gerao (autossmica dominante). J a hipermetropia elevada herdada dos pais (autossmica recessiva), explicou a especialista. A mdica ainda relatou a importncia em identificar, prematuramente, o comportamento hipermtrope da criana, caso contrrio, esse problema pode afetar a rotina visual e funcional delas. A falta de correo da hipermetropia pode dificultar o processo de aprendizado, e ainda pode reduzir, ou limitar, o desenvolvimento nas atividades da criana. Em alguns casos, pode ser responsvel por repetncia, evaso escolar e dificuldade na socializao, requerendo aes de identificao e tratamento, concluiu a Dra. Liana. Os sintomas relacionados hipermetropia, alm da dificuldade de enxergar de perto, variam entre: dores de cabea, fadiga ocular e dificuldade de concentrao em leitura.(...) O tratamento utilizado para corrigir este tipo de anomalia realizado atravs da cirurgia refrativa. O uso de culos (com lentes esfricas) ou lentes de contato corretivas considerado mtodo convencional, que pode solucionar o problema visual do hipermtrope. Disponvel em: www.cbo.net.br/novo/publicacao/revista_vejabem. Acesso em: 18 fev. 2017. De acordo com o texto acima, a hipermetropia pode ser corrigida com o uso de lentes esfricas. Dessa maneira, uma lente corretiva, delgada e gaussiana, de vergncia igual a +2 di,conforme figura a seguir, utilizada para projetar, num anteparo colocado a uma distncia p da lente,a imagem de um corpo luminoso que oscila em movimento harmnico simples (MHS). A equao que descreve o movimento oscilatrio desse corpo . Considere que a equao que descreve a oscilao projetada no anteparo dada por. Nessas condies, a distncia p, em cm,

(AFA - 2018) Um sistema gasoso constitudo por n mols de um gs perfeito passa do estado x para o estado y por meio dos processos distintos 1 e 2 mostrados no esquema a seguir. Se no processo 2 o sistema realiza um trabalho de 200 Je absorve uma quantidade de calor de 500 J correto afirmar que

(AFA - 2018) Em muitos problemas de fsica desprezam-se as foras de resistncia ao movimento. Entretanto, sabe-se que, na prtica, essas foras so significativas e muitas vezes desempenham um papel determinante. Por exemplo, no automobilismo, os veculos comumente possuem dispositivos aerodinmicos implementados, os quais tm a funo de contribuir para o aumento da Downforce, uma fora vertical, inversa sustentao, que busca incrementar a aderncia dos pneus ao asfalto atravs de um acrscimo na carga normal, permitindo que o veculo possa realizar as curvas com uma velocidade maior do que o faria sem estes dispositivos. (Trecho retirado da monografia intitulada Sistema ativo de reduo de arrasto aerodinmico por atuador aplicado a um prottipo de frmula SAE, de autoria de Danilo Barbosa Porto, apresentada na Escola de Engenharia de So Carlos, da Universidade de So Paulo, em 2016). Para avaliar o papel da Downforce, considere um carro de Frmula 1, de massa M, realizando uma curva em determinada pista plana. Ao se desprezar completamente os efeitos produzidos pelo seu movimento em relao ao ar, mas considerando o atrito entre pneus e o asfalto, o carro consegue fazer a curva, sem derrapar, a uma velocidade mxima V. Porm, ao levar em conta, especificamente, a atuao da Downforce D (desconsiderando a fora de arrasto) a velocidade mxima V do carro, nessa mesma curva, muda em funo de D. Nessas condies, o grfico que melhor representa a relao em funo de D

(AFA - 2018) Uma fonte sonora A, em repouso, emite um sinalsonoro de frequncia constanteUm sensordesloca-se com velocidade constante,em relao Terra, sobre um plano perfeitamente retilneo, em direo fonte sonora, como mostra a Figura 1. O sensor registra a frequncia aparente devido sua movimentao em relao fonte sonora e a reenvia para um laboratrio onde um sistema de caixas sonoras, acopladas a trs tubos sonoros, de comprimentos L1, L2 e L3,reproduz essa frequncia aparente fazendo com que as colunas de ar desses tubos vibrem produzindo os harmnicos apresentados na Figura 2. Considere que o sensor se movimenta em um local onde a velocidade do som constante e igual a 320 m/s,que os tubos sonoros possuam dimetros muito menores do que seus respectivos comprimentos e que a velocidade do som no interior desses tubos seja tambm constante e igual a 320 m/s. Considere tambm que a fonte A e o arestejam em repouso em relao Terra. Nessas condies, correto afirmar que os comprimentosL1, L2 e L3,respectivamente, em metros, so

(AFA - 2018) Quando necessrio, use: Acelerao da gravidade: Velocidade da luz no vcuo: Constante de Planck: Potencial eltrico no infinito: zero. Uma partcula abandonada sobre um plano inclinado, a partir do repouso no ponto A, de altura h,como indicado pela figura (fora de escala). Aps descer o plano inclinado, a partcula se move horizontalmente at atingir o ponto B.As foras de resistncia ao movimento de A at B so desprezveis. A partir do ponto B,a partcula ento cai, livre da ao de resistncia do ar, em um poo de profundidade igual a 3h e dimetro x.Ela colide com o cho do fundo do poo e sobe, em uma nova trajetria parablica at atingir o ponto C,o mais alto dessa nova trajetria. Na coliso com o fundo do poo a partcula perde 50%de sua energia mecnica. Finalmente, do ponto C ao ponto D, apartcula move-se horizontalmente experimentando atrito com a superfcie. Aps percorrer a distncia entre C e D, igual a 3h, a partcula atinge o repouso. Considerando que os pontosB e Cesto na borda do poo, que o coeficiente de atrito dinmico entre a partcula e o trecho igual a 0,5e que durante a coliso com o fundo do poo a partcula no desliza, a razo entre o dimetro do poo e a altura de onde foi abandonada a partcula,vale

(AFA - 2018) TEXTO PARA A PRXIMA QUESTO. FOOD SHORTAGE CAUSES, EFFECTS AND SOLUTIONS Food shortage is a serious problem facing the world and is prevalent in sub-Saharan Africa. The scarcity of food is caused by economic, environmental and social factors such as crop failure, overpopulation and poor government policies are the main cause of food scarcity in most countries. Environmental factors determine the kind of crops to be produced in a given place, economic factors determine the buying and production capacity and socio-political factors determine distribution of food to the masses. Food shortage has far reaching long and short term negative impacts which include starvation, malnutrition, increased mortality and political unrest1. There is need to collectively address the issue of food insecurity using both emergency and long term measures. Causes of food shortages There are a number of social factors causing food shortages. The rate of population increase is higher than increase in food production. The world is consuming more than it is producing, leading to decline in food stock and storage level and increased food prices due to soaring2 demand. Increased population has led to clearing of agricultural land for human settlement reducing agricultural production (Kamdor, 2007). Overcrowding of population in a given place results in urbanization of previously rich agricultural fields. Destruction of forests for human settlement, particularly tropical rain forest has led to climatic changes, such as prolonged droughts and desertification. Population increase means more pollution as people use more fuel in cars, industry, domestic cooking. The resultant effect is increased air and water pollution which affect the climate and food production. Environmental factors have greatly contributed to food shortage. Climatic change has reduced agricultural production. The change in climate is majorly caused by human activities and to some small extent natural activities. Increased combustion of fossil fuels due to increasing population through power plant, motor transport and mining of coal and oil emits green house gases which have continued to affect world climate. Deforestation of tropical forest due to human pressure has changed climatic patterns and rainfall seasons, and led to desertification which cannot support a crop production. Land degradation due to increased human activities has impacted negatively on agricultural production (Kamdor, 2007). Natural disasters such as floods, tropical storms and prolonged droughts are on the increase and have devastating impacts on food security particularly in developing countries. There are several economic factors that contribute to food shortage. Economic factors affect the ability of farmers to engage in agricultural production. Poverty situation in developing nations have reduced their capacity to produce food, as most farmers cannot afford seed and fertilizers. They use poor farming methods that cannot yield3 enough, even substantial use. Investments in agricultural research and developing are very low in developing nations. Recent global financial crisis have led to increase in food prices and reduced investments in agriculture by individuals and governments in developed nations resulting in reduced food production. Effects of food shortage There are a number of short term effects of food shortage. The impact on children, mothers and elderly are very evident as seen in malnutrition and hunger related deaths. Children succumb to hunger within short period as they cannot stand long period of starvation and they die even before the arrival of emergency assistance. There are also long term effects of food shortage. These include increase in the price of food as a result demand and supply forces. Increasing cost of food production due to the increase in fuel prices coupled with persistent drought in grain producing regions has contributed to the increase in the price of food in the world. Increase in oil price led to increase in the price of fertilizers, transportation of food and also industrial agriculture. Increasing food prices culminated in political instability and social unrest in several nations across the globe in 2007, in countries of Mexico, Cameroon, Brazil, Burkina Faso, Pakistan, Egypt and Bangladesh among other nations (Kamdor, 2007). Solution to problem of food shortage There are some solutions to the problem of food shortage. There is need to reduce production of carbon emissions and pollution to reduce the resultant climatic change through concerted and individual efforts. There is need to invest in clean energy such as solar, nuclear, and geothermal power in homes and industries, because they dont have adverse effects on the environment (Kamdor, 2007). Rich nations should help poor nations to develop and use clean and renewable energy in order to stabilize green house emissions into the atmosphere (Watson, nd). Government need to work in consultation with climatic bodies, World Bank and the UN to engage in projects aimed at promoting green environment. Conclusion Causes of food shortage are well known and can be solved if appropriate measures to solve the problem are taken and effectively implemented. Environmental causes of food shortages are changes in climatic and pollution due to human activities such overgrazing4 and deforestation which can be controlled through legislation. (Adapted from http://www.paypervids.com/food-shortage-causes- effects-solutions/Acesso em:14 fev 2017) Glossary: 1. unrest disagreement or fighting between different groups of people 2. soaring something that increases rapidly above the usual level 3. yield to supply or produce something such as profit or an amount or food 4. overgrazing excessive use of land where animals feed on grass Starvation, malnutrition, increased mortality and political unrest are mentioned in the text as examples of

(AFA - 2018) TEXTO PARA A PRXIMA QUESTO. FOOD SHORTAGE CAUSES, EFFECTS AND SOLUTIONS Food shortage is a serious problem facing the world and is prevalent in sub-Saharan Africa. The scarcity of food is caused by economic, environmental and social factors such as crop failure, overpopulation and poor government policies are the main cause of food scarcity in most countries. Environmental factors determine the kind of crops to be produced in a given place, economic factors determine the buying and production capacity and socio-political factors determine distribution of food to the masses. Food shortage has far reaching long and short term negative impacts which include starvation, malnutrition, increased mortality and political unrest1. There is need to collectively address the issue of food insecurity using both emergency and long term measures. Causes of food shortages There are a number of social factors causing food shortages. The rate of population increase is higher than increase in food production. The world is consuming more than it is producing, leading to decline in food stock and storage level and increased food prices due to soaring2 demand. Increased population has led to clearing of agricultural land for human settlement reducing agricultural production (Kamdor, 2007). Overcrowding of population in a given place results in urbanization of previously rich agricultural fields. Destruction of forests for human settlement, particularly tropical rain forest has led to climatic changes, such as prolonged droughts and desertification. Population increase means more pollution as people use more fuel in cars, industry, domestic cooking. The resultant effect is increased air and water pollution which affect the climate and food production. Environmental factors have greatly contributed to food shortage. Climatic change has reduced agricultural production. The change in climate is majorly caused by human activities and to some small extent natural activities. Increased combustion of fossil fuels due to increasing population through power plant, motor transport and mining of coal and oil emits green house gases which have continued to affect world climate. Deforestation of tropical forest due to human pressure has changed climatic patterns and rainfall seasons, and led to desertification which cannot support a crop production. Land degradation due to increased human activities has impacted negatively on agricultural production (Kamdor, 2007). Natural disasters such as floods, tropical storms and prolonged droughts are on the increase and have devastating impacts on food security particularly in developing countries. There are several economic factors that contribute to food shortage. Economic factors affect the ability of farmers to engage in agricultural production. Poverty situation in developing nations have reduced their capacity to produce food, as most farmers cannot afford seed and fertilizers. They use poor farming methods that cannot yield3 enough, even substantial use. Investments in agricultural research and developing are very low in developing nations. Recent global financial crisis have led to increase in food prices and reduced investments in agriculture by individuals and governments in developed nations resulting in reduced food production. Effects of food shortage There are a number of short term effects of food shortage. The impact on children, mothers and elderly are very evident as seen in malnutrition and hunger related deaths. Children succumb to hunger within short period as they cannot stand long period of starvation and they die even before the arrival of emergency assistance. There are also long term effects of food shortage. These include increase in the price of food as a result demand and supply forces. Increasing cost of food production due to the increase in fuel prices coupled with persistent drought in grain producing regions has contributed to the increase in the price of food in the world. Increase in oil price led to increase in the price of fertilizers, transportation of food and also industrial agriculture. Increasing food prices culminated in political instability and social unrest in several nations across the globe in 2007, in countries of Mexico, Cameroon, Brazil, Burkina Faso, Pakistan, Egypt and Bangladesh among other nations (Kamdor, 2007). Solution to problem of food shortage There are some solutions to the problem of food shortage. There is need to reduce production of carbon emissions and pollution to reduce the resultant climatic change through concerted and individual efforts. There is need to invest in clean energy such as solar, nuclear, and geothermal power in homes and industries, because they dont have adverse effects on the environment (Kamdor, 2007). Rich nations should help poor nations to develop and use clean and renewable energy in order to stabilize green house emissions into the atmosphere (Watson, nd). Government need to work in consultation with climatic bodies, World Bank and the UN to engage in projects aimed at promoting green environment. Conclusion Causes of food shortage are well known and can be solved if appropriate measures to solve the problem are taken and effectively implemented. Environmental causes of food shortages are changes in climatic and pollution due to human activities such overgrazing4 and deforestation which can be controlled through legislation. (Adapted from http://www.paypervids.com/food-shortage-causes- effects-solutions/Acesso em:14 fev 2017) Glossary: 1. unrest disagreement or fighting between different groups of people 2. soaring something that increases rapidly above the usual level 3. yield to supply or produce something such as profit or an amount or food 4. overgrazing excessive use of land where animals feed on grass Overcrowding of population (line 25) in the text means a

(AFA - 2018) Quando necessrio use: - Acelereao da gravidade: g = 10 m/s2; - sen 19 = cos 71 = 0,3; - sen 71 = cos 19 = 0,9; - Velocidade da luz no vcuo: c = 3,0108m/s; - Constante de Planck: h = 6,610-34Js; - 1 eV = 1,610-19J; - Potencial eltrico no infinito: zero. SECA VIRA TEMA DE EXCURSO E AULA DE CINCIA EM ESCOLAS Thais Bilenky de So Paulo 26/10/2014 02h00 (...) Como no Vera Cruz, a crise da gua tem motivado atividades em diversos colgios da cidade. Na rede municipal, 34escolas ficaram sem gua na semana passada. A Secretaria de Educao diz que incentiva debates sobre o tema e sua incluso em projetos interdisciplinares. Nas escolas particulares, problemas de abastecimento no so comuns. A falta de gua abordada para efeito pedaggico como no colgio Rio Branco, que tem promovido bate-papos e estudos. (...) Disponvel em: www1.folha.uol.com.br/cotidiano. Acesso em: 14 fev. 2017. Motivado pelo trecho do artigo acima exposto, um professor de fsica lanou um desafio para os alunos do 3 ano em uma escola onde, frequentemente, falta gua. Tal desafio consistia em determinar o volume dgua em um reservatrio de difcil acesso. Para a determinao deste volume dgua os alunos deveriam utilizar somente um circuito eltrico constitudo de um voltmetro ideal V,uma bateria de femigual a 12 Ve resistncia interna igual a 1, alm de um resistor hmico Rigual a 2e um reostato AB,feito de material de resistividade eltrica constante, cuja resistncia eltrica pode variar de 0a 4,de acordo com a posio da boia que ajustada pela altura do nvel dgua do reservatrio. Depois de algum tempo, os alunos apresentaram o projeto ao professor, conforme esquematizado na figura a seguir. De acordo com o projeto, o volume dgua no reservatrio pode ser calculado por meio da ddp nos terminais da bateria, registrada pelo voltmetro. Sendo a capacidade mxima deste reservatrio igual a 20 m3,desconsiderando as resistncias eltricas dos fios de ligao que esto isolados e o atrito do suporte da boia com o reostato, quando o voltmetro indicar 9,0 V,o volume dgua neste reservatrio ser, em m3, igual a:

(AFA - 2018) Os carregadores de bateria sem fio de smartphones, tambm conhecidos como carregadores wireless, so dispositivos compostos de bobina e ligados rede eltrica, que carregam as baterias dos aparelhos apenas pela proximidade, atravs do fenmeno de induo eletromagntica. Para isso, o smartphone deve ser apto referida tecnologia, ou seja, tambm possuir uma bobina, para que nela surja uma fora eletromotriz induzida que carregar a bateria. Se na bobina de um carregador (indutora), paralela e concntrica com a bobina de um smartphone (induzida), passa uma corrente, comem segundos,o grfico que melhor representa a fora eletromotriz induzida () na bobina do smartphone, em funo do tempo

(AFA - 2018) O grfico seguinte representa a velocidade escalar vde uma partcula em movimento retilneo. Considerando que, em t = 0a partcula est na origem dos espaos ,o grfico que melhor representa a posio (S)dessa partcula at o instante t = 5 s

(AFA - 2018) TEXTO PARA A PRXIMA QUESTO. FOOD SHORTAGE CAUSES, EFFECTS AND SOLUTIONS Food shortage is a serious problem facing the world and is prevalent in sub-Saharan Africa. The scarcity of food is caused by economic, environmental and social factors such as crop failure, overpopulation and poor government policies are the main cause of food scarcity in most countries. Environmental factors determine the kind of crops to be produced in a given place, economic factors determine the buying and production capacity and socio-political factors determine distribution of food to the masses. Food shortage has far reaching long and short term negative impacts which include starvation, malnutrition, increased mortality and political unrest1. There is need to collectively address the issue of food insecurity using both emergency and long term measures. Causes of food shortages There are a number of social factors causing food shortages. The rate of population increase is higher than increase in food production. The world is consuming more than it is producing, leading to decline in food stock and storage level and increased food prices due to soaring2 demand. Increased population has led to clearing of agricultural land for human settlement reducing agricultural production (Kamdor, 2007). Overcrowding of population in a given place results in urbanization of previously rich agricultural fields. Destruction of forests for human settlement, particularly tropical rain forest has led to climatic changes, such as prolonged droughts and desertification. Population increase means more pollution as people use more fuel in cars, industry, domestic cooking. The resultant effect is increased air and water pollution which affect the climate and food production. Environmental factors have greatly contributed to food shortage. Climatic change has reduced agricultural production. The change in climate is majorly caused by human activities and to some small extent natural activities. Increased combustion of fossil fuels due to increasing population through power plant, motor transport and mining of coal and oil emits green house gases which have continued to affect world climate. Deforestation of tropical forest due to human pressure has changed climatic patterns and rainfall seasons, and led to desertification which cannot support a crop production. Land degradation due to increased human activities has impacted negatively on agricultural production (Kamdor, 2007). Natural disasters such as floods, tropical storms and prolonged droughts are on the increase and have devastating impacts on food security particularly in developing countries. There are several economic factors that contribute to food shortage. Economic factors affect the ability of farmers to engage in agricultural production. Poverty situation in developing nations have reduced their capacity to produce food, as most farmers cannot afford seed and fertilizers. They use poor farming methods that cannot yield3 enough, even substantial use. Investments in agricultural research and developing are very low in developing nations. Recent global financial crisis have led to increase in food prices and reduced investments in agriculture by individuals and governments in developed nations resulting in reduced food production. Effects of food shortage There are a number of short term effects of food shortage. The impact on children, mothers and elderly are very evident as seen in malnutrition and hunger related deaths. Children succumb to hunger within short period as they cannot stand long period of starvation and they die even before the arrival of emergency assistance. There are also long term effects of food shortage. These include increase in the price of food as a result demand and supply forces. Increasing cost of food production due to the increase in fuel prices coupled with persistent drought in grain producing regions has contributed to the increase in the price of food in the world. Increase in oil price led to increase in the price of fertilizers, transportation of food and also industrial agriculture. Increasing food prices culminated in political instability and social unrest in several nations across the globe in 2007, in countries of Mexico, Cameroon, Brazil, Burkina Faso, Pakistan, Egypt and Bangladesh among other nations (Kamdor, 2007). Solution to problem of food shortage There are some solutions to the problem of food shortage. There is need to reduce production of carbon emissions and pollution to reduce the resultant climatic change through concerted and individual efforts. There is need to invest in clean energy such as solar, nuclear, and geothermal power in homes and industries, because they dont have adverse effects on the environment (Kamdor, 2007). Rich nations should help poor nations to develop and use clean and renewable energy in order to stabilize green house emissions into the atmosphere (Watson, nd). Government need to work in consultation with climatic bodies, World Bank and the UN to engage in projects aimed at promoting green environment. Conclusion Causes of food shortage are well known and can be solved if appropriate measures to solve the problem are taken and effectively implemented. Environmental causes of food shortages are changes in climatic and pollution due to human activities such overgrazing4 and deforestation which can be controlled through legislation. (Adapted from http://www.paypervids.com/food-shortage-causes- effects-solutions/Acesso em:14 fev 2017) Glossary: 1. unrest disagreement or fighting between different groups of people 2. soaring something that increases rapidly above the usual level 3. yield to supply or produce something such as profit or an amount or food 4. overgrazing excessive use of land where animals feed on grass Investing in clean energy is considered

(AFA - 2018) - Questo adaptada. FOOD SHORTAGE CAUSES, EFFECTS AND SOLUTIONS Food shortage is a serious problem facing the world and is prevalent in sub-Saharan Africa. The scarcity of food is caused by economic, environmental and social factors such as crop failure, overpopulation and poor government policies are the main cause of food scarcity in most countries. Environmental factors determine the kind of crops to be produced in a given place, economic factors determine the buying and production capacity and socio-political factors determine distribution of food to the masses. Food shortage has far reaching long and short term negative impacts which include starvation, malnutrition, increased mortality and political unrest. There is need to collectively address the issue of food insecurity using both emergency and long term measures. Causes of food shortages There are a number of social factors causing food shortages. The rate of population increase is higher than increase in food production. The world is consuming more than it is producing, leading to decline in food stock and storage level and increased food prices due to soaring demand. Increased population has led to clearing of agricultural land for human settlement reducing agricultural production (Kamdor, 2007). Overcrowding of population in a given place results in urbanization of previously rich agricultural fields. Destruction of forests for human settlement, particularly tropical rain forest has led to climatic changes, such as prolonged droughts and desertification. Population increase means more pollution as people use more fuel in cars, industry, domestic cooking. The resultant effect is increased air and water pollution which affect the climate and food production. Environmental factors have greatly contributed to food shortage. Climatic change has reduced agricultural production. The change in climate is majorly caused by human activities and to some small extent natural activities. Increased combustion of fossil fuels due to increasing population through power plant, motor transport and mining of coal and oil emits green house gases which have continued to affect world climate. Deforestation of tropical forest due to human pressure has changed climatic patterns and rainfall seasons, and led to desertification which cannot support a crop production. Land degradation due to increased human activities has impacted negatively on agricultural production (Kamdor, 2007). Natural disasters such as floods, tropical storms and prolonged droughts are on the increase and have devastating impacts on food security particularly in developing countries. There are several economic factors that contribute to food shortage. Economic factors affect the ability of farmers to engage in agricultural production. Poverty situation in developing nations have reduced their capacity to produce food, as most farmers cannot afford seed and fertilizers. They use poor farming methods that cannot yield enough, even substantial use. Investments in agricultural research and developing are very low in developing nations. Recent global financial crisis have led to increase in food prices and reduced investments in agriculture by individuals and governments in developed nations resulting in reduced food production. Effects of food shortage There are a number of short term effects of food shortage. The impact on children, mothers and elderly are very evident as seen in malnutrition and hunger related deaths. Children succumb to hunger within short period as they cannot stand long period of starvation and they die even before the arrival of emergency assistance. There are also long term effects of food shortage. These include increase in the price of food as a result demand and supply forces. Increasing cost of food production due to the increase in fuel prices coupled with persistent drought in grain producing regions has contributed to the increase in the price of food in the world. Increase in oil price led to increase in the price of fertilizers, transportation of food and also industrial agriculture. Increasing food prices culminated in political instability and social unrest in several nations across the globe in 2007, in countries of Mexico, Cameroon, Brazil, Burkina Faso, Pakistan, Egypt and Bangladesh among other nations (Kamdor, 2007). Solution to problem of food shortage There are some solutions to the problem of food shortage. There is need to reduce production of carbon emissions and pollution to reduce the resultant climatic change through concerted and individual efforts. There is need to invest in clean energy such as solar, nuclear, and geothermal power in homes and industries, because they dont have adverse effects on the environment (Kamdor, 2007). Rich nations should help poor nations to develop and use clean and renewable energy in order to stabilize green house emissions into the atmosphere (Watson, nd). Government need to work in consultation with climatic bodies, World Bank and the UN to engage in projects aimed at promoting green environment. Conclusion Causes of food shortage are well known and can be solved if appropriate measures to solve the problem are taken and effectively implemented. Environmental causes of food shortages are changes in climatic and pollution due to human activities such overgrazing and deforestation which can be controlled through legislation. (Adapted from http://www.paypervids.com/food-shortage-causes- effects-solutions/Acesso em:14 fev 2017) Glossary: 1. unrest disagreement or fighting between different groups of people 2. soaring something that increases rapidly above the usual level 3. yield to supply or produce something such as profit or an amount or food The personal pronoun they underlined refers to

(AFA - 2018) FOOD SHORTAGE CAUSES, EFFECTS AND SOLUTIONS Food shortage is a serious problem facing the world and is prevalent in sub-Saharan Africa. The scarcity of food is caused by economic, environmental and social factors such as crop failure, overpopulation and poor government policies are the main cause of food scarcity in most countries. Environmental factors determine the kind of crops to be produced in a given place, economic factors determine the buying and production capacity and socio-political factors determine distribution of food to the masses. Food shortage has far reaching long and short term negative impacts which include starvation, malnutrition, increased mortality and political unrest1. There is need to collectively address the issue of food insecurity using both emergency and long term measures. Causes of food shortages There are a number of social factors causing food shortages. The rate of population increase is higher than increase in food production. The world is consuming more than it is producing, leading to decline in food stock and storage level and increased food prices due to soaring2 demand. Increased population has led to clearing of agricultural land for human settlement reducing agricultural production (Kamdor, 2007). Overcrowding of population in a given place results in urbanization of previously rich agricultural fields. Destruction of forests for human settlement, particularly tropical rain forest has led to climatic changes, such as prolonged droughts and desertification. Population increase means more pollution as people use more fuel in cars, industry, domestic cooking. The resultant effect is increased air and water pollution which affect the climate and food production. Environmental factors have greatly contributed to food shortage. Climatic change has reduced agricultural production. The change in climate is majorly caused by human activities and to some small extent natural activities. Increased combustion of fossil fuels due to increasing population through power plant, motor transport and mining of coal and oil emits green house gases which have continued to affect world climate. Deforestation of tropical forest due to human pressure has changed climatic patterns and rainfall seasons, and led to desertification which cannot support a crop production. Land degradation due to increased human activities has impacted negatively on agricultural production (Kamdor, 2007). Natural disasters such as floods, tropical storms and prolonged droughts are on the increase and have devastating impacts on food security particularly in developing countries. There are several economic factors that contribute to food shortage. Economic factors affect the ability of farmers to engage in agricultural production. Poverty situation in developing nations have reduced their capacity to produce food, as most farmers cannot afford seed and fertilizers. They use poor farming methods that cannot yield3 enough, even substantial use. Investments in agricultural research and developing are very low in developing nations. Recent global financial crisis have led to increase in food prices and reduced investments in agriculture by individuals and governments in developed nations resulting in reduced food production. Effects of food shortage There are a number of short term effects of food shortage. The impact on children, mothers and elderly are very evident as seen in malnutrition and hunger related deaths. Children succumb to hunger within shortperiod as they cannot stand long period of starvation and they die even before the arrival of emergency assistance. There are also long term effects of food shortage. These include increase in the price of food as a result demand and supply forces. Increasing cost of food production due to the increase in fuel prices coupled with persistent drought in grain producing regions has contributed to the increase in the price of food in the world. Increase in oil price led to increase in the price of fertilizers, transportation of food and also industrial agriculture. Increasing food prices culminated in political instability and social unrest in several nations across the globe in 2007, in countries of Mexico, Cameroon, Brazil, Burkina Faso, Pakistan, Egypt and Bangladesh among other nations (Kamdor, 2007). Solution to problem of food shortage There are some solutions to the problem of food shortage. There is need to reduce production of carbon emissions and pollution to reduce the resultant climatic change through concerted and individual efforts. There is need to invest in clean energy such as solar, nuclear, and geothermal power in homes and industries, because they dont have adverse effects on the environment (Kamdor, 2007). Rich nations should help poor nations to develop and use clean and renewable energy in order to stabilize green house emissions into the atmosphere (Watson, nd). Government need to work in consultation with climatic bodies, World Bank and the UN to engage in projects aimed at promoting green environment. Conclusion Causes of food shortage are well known and can be solved if appropriate measures to solve the problem are taken and effectively implemented. Environmental causes of food shortages are changes in climatic and pollution due to human activities such overgrazing4 and deforestation which can be controlled through legislation. (Adapted from http://www.paypervids.com/food-shortage-causes- effects-solutions/Acesso em:14 fev 2017) Glossary: 1. unrest disagreement or fighting between different groups of people 2. soaring something that increases rapidly above the usual level 3. yield to supply or produce something such as profit or an amount or food 4. overgrazing excessive use of land where animals feed on grass Mark the option which best shows the meaning of the highlighted expression in deforestation of tropical forest due to human pressure (line 42)

(AFA - 2018) Quando necessrio use: - Acelereao da gravidade: g = 10 m/s2; - sen 19 = cos 71 = 0,3; - sen 71 = cos 19 = 0,9; - Velocidade da luz no vcuo: c = 3,0108m/s; - Constante de Planck: h = 6,610-34Js; - 1 eV = 1,610-19J; Uma rampa, homognea, de massa m e comprimento L, inicialmente colocada na horizontal. A extremidade A,dessa rampa, encontra-se acoplada a uma articulao sem atrito. Na extremidade Best sentado, em repouso, um garoto, tambm de massa m.Essa extremidade Best presa ao cho, por um fio ideal, e ao teto, por uma mola ideal, de constante elstica k, conforme ilustra a Figura 1. Em um determinado instante o garoto corta o fio. A mola, que est inicialmente deformada de um valorx,passa a erguer lentamente a extremidade B da rampa,fazendo com que o garoto escorregue, sem atrito e sem perder o contato com a rampa, at a extremidade A,conforme Figura 2. Quando o garoto, que neste caso deve ser tratado como partcula, atinge a extremidadeA,a mola se encontra em seu comprimento natural (sem deformao) e a rampa estar em repouso e inclinada de um ngulo. Considerando go mdulo da acelerao da gravidade local, nessas condies, a velocidade do garoto em A, vale

(AFA - 2018) Quando necessrio use : - Acelerao da gravidade: - sen 19C = cos 71 = 0,3; - sen 71 = cos 19 = 0,9; - Velocidade da luz no vcuo: - Constante de Planck: - 1 e V =; - Potencial eltrico no infinito: zero. Considere dois tubos cilndricos (1 e 2), verticais, idnticos e feitos do mesmo material, contendo um mesmo lquido em equilbrio at a altura de 50,0 cm ,conforme figura a seguir. As temperaturas nos dois tubos so inicialmente iguais e de valor 35CO tubo 1 resfriado at 0Cenquanto o tubo 2 aquecido at 70Ce a altura do lquido em cada tubo passa a ser o valor indicado na figura. Sabendo-se que o coeficiente de dilatao trmica dos tubos desprezvel quando comparado com o do lquido, o coeficiente de dilatao volumtrica do lquido, considerado constante, , em