A block, moving on a frictionless horizontal surface on Earth, requires a force if it is to be stopped. Now suppose that the same block, moving with the same speed on a frictionless horizontal surface on the Moon, where gravity is less, is to be stopped in the same time. We can say that, compared to the Earth,
A) less force is required to stop the block on the Moon.
B) the force required would be the same.
C) greater force is required to stop the block on the Moon.
D) the block could not be stopped.

Question

Quizplus · Accepted Answer

The force required to stop the block depends on its mass and the change in velocity (deceleration), not on the gravitational field where the action takes place. Since gravity does not affect horizontal motion directly and the scenario specifies a frictionless surface, the force required to stop the block in the same amount of time would be the same on both the Earth and the Moon.

A Block, Moving on a Frictionless Horizontal Surface on Earth