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Escape speed from Earth is

How does the force of gravity between two bodies change when distance between them is doubled?

The equilibrium rule ΣF = 0 applies to

The gravitational force decreases between a pair of planets when they get farther apart.

The force that propels a heavy truck along a highway is provided by

For a satellite in an elliptical orbit around Earth, both gravitational force and speed remain unchanged everywhere.

When a 25-kg block is simultaneously pushed to the left with 20 N, and to the right with 20 N, the net force on the block is

A simple machine cannot multiply

A machine puts out 100 W of power for every 1000 W put into it. The efficiency of the machine is

When a lemming jumps off a cliff, Earth pulls it downward. The reaction to this force is