Question #27527

State against each observation below whether it is true or false. Give reasons for your answer.

i. The angular momentum of an artificial satellite rotating about the earth under its gravitation

varies with time

ii. An alpha particle scattered from an atomic nucleus moves in a plane.

iii. An artificial satellite moves at greater speed when it is nearer the earth.

i. The angular momentum of an artificial satellite rotating about the earth under its gravitation

varies with time

ii. An alpha particle scattered from an atomic nucleus moves in a plane.

iii. An artificial satellite moves at greater speed when it is nearer the earth.

Expert's answer

i. False

Angular momentum can not change, because force acting on the satellite (gravitational force) is oriented along the radius-vector that connects satellite and the center of orbit. Force torque is 0, and so, it can not change angular momentum of satellite

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ii. True

This is true, because force, acting on particle, is central force - it acts along the vector that connects the alpha particle and nucleus and this vector is in plane of motion. Hence, there will be no z-component of acceleration and of motion.

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iii. True

When satellite comes closer to Earth, its potential energy decreases. Because of energy conservation law, the kinetic energy increases on the same amount, and thus, it has greater speed.

Angular momentum can not change, because force acting on the satellite (gravitational force) is oriented along the radius-vector that connects satellite and the center of orbit. Force torque is 0, and so, it can not change angular momentum of satellite

&

ii. True

This is true, because force, acting on particle, is central force - it acts along the vector that connects the alpha particle and nucleus and this vector is in plane of motion. Hence, there will be no z-component of acceleration and of motion.

&

iii. True

When satellite comes closer to Earth, its potential energy decreases. Because of energy conservation law, the kinetic energy increases on the same amount, and thus, it has greater speed.

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