Author Question: If the Earth had twice its present radius and twice its present mass, what change in weight would ... (Read 74 times)

future617RT · **on:** Jul 29, 2018

If the Earth had twice its present radius and twice its present mass, what change in weight would you experience? Explain.

What will be an ideal response?

Question 2

Why does a satellite in elliptical orbit gain speed as it moves closer to the planet? When is its kinetic energy greatest? Least? Where is its potential energy greatest? The least?

What will be an ideal response?

lauravaras · **Reply #1 on:** Jul 29, 2018

Answer to Question 1

Answer: If only the radius of the Earth were doubled, you'd have one-quarter your weight. If only the mass of the Earth were doubled, you'd have twice your weight. Taken together, your weight would be half. The gravitational equation nicely guides this answer.

Answer to Question 2

Answer: The sum of a satellite's potential and kinetic energies remains constant if the satellite is in a closed orbit about a planet. As the satellite moves closer to the planet, it falls with gravity and gains speed. Potential energy decreases, kinetic energy correspondingly increases, and hence speed increases. As it moves farther from the planet, it moves against gravity, its kinetic energy decreases, and its potential energy increases. Its potential energy is greatest when the satellite is farthest from the planet, and least when it is closest to the planet.