Earth has an external heat engine. The heat that is produced by the Sun powers various processes of life on Earth. Sunlight is needed by plants for photosynthesis and is therefore necessary to sustain life on Earth. Correct answer: Erosion is a result of Earth’s external heat engine, powered by the Sun. Hence, the correct answer is option a. Reason for correct answer: Option a. is given as “the Sun.” Erosion is caused by the effect of surface processes (like the wind, water, sun). These cause wearing of rocks and removal of the upper layer of soil. Solar energy is very important for life on Earth as it helps in sustaining life. Solar energy powers all life processes on Earth and acts as the external heat engine. Solar energy also leads to wearing of the crust of Earth and leads to erosion. Therefore, erosion is a result of Earth’s external heat engine, powered by heat from the Sun. Reason for incorrect answer: Option b. is given as, “gravity.” Gravity is the force by which all objects are attracted towards the centre of Earth. Erosion is not due to gravity. Hence, option b. is incorrect. Option c. is given as, “heat flowing from Earth’s interior outward.” Earth’s internal heat engine is powered by heat flowing from Earth’s interior outward and not the external heat engine. Hence, option c. is incorrect. Option d. is given as, “the Earth’s magnetic field.” The magnetic field of Earth is due to the movement of metal present in the core and mantle of Earth. This does not contribute to erosion. Hence, option d. is incorrect. Hence, the options b. , c. and d. are incorrect. Conclusion: Earth has an external heat engine which is powered by the Sun. Thus, the correct option is a.
Earth has an external heat engine. The heat that is produced by the Sun powers various processes of life on Earth. Sunlight is needed by plants for photosynthesis and is therefore necessary to sustain life on Earth. Correct answer: Erosion is a result of Earth’s external heat engine, powered by the Sun. Hence, the correct answer is option a. Reason for correct answer: Option a. is given as “the Sun.” Erosion is caused by the effect of surface processes (like the wind, water, sun). These cause wearing of rocks and removal of the upper layer of soil. Solar energy is very important for life on Earth as it helps in sustaining life. Solar energy powers all life processes on Earth and acts as the external heat engine. Solar energy also leads to wearing of the crust of Earth and leads to erosion. Therefore, erosion is a result of Earth’s external heat engine, powered by heat from the Sun. Reason for incorrect answer: Option b. is given as, “gravity.” Gravity is the force by which all objects are attracted towards the centre of Earth. Erosion is not due to gravity. Hence, option b. is incorrect. Option c. is given as, “heat flowing from Earth’s interior outward.” Earth’s internal heat engine is powered by heat flowing from Earth’s interior outward and not the external heat engine. Hence, option c. is incorrect. Option d. is given as, “the Earth’s magnetic field.” The magnetic field of Earth is due to the movement of metal present in the core and mantle of Earth. This does not contribute to erosion. Hence, option d. is incorrect. Hence, the options b. , c. and d. are incorrect. Conclusion: Earth has an external heat engine which is powered by the Sun. Thus, the correct option is a.
