Question

A block of certain mass is sliding on a smooth floor with a certain velocity. The work required to stop it is

• A. Negative
• B. Equal to the potential energy of the block
• C. Equal to the kinetic energy of the block
• D. Positive

Answer 1

Answer: (A), (C)

The correct options are
A

Negative

C

Equal to the kinetic energy of the block

In order to stop a moving block, we have to apply force in the opposite direction. Since the force is applied in the opposite direction, this will be negative work. Since the body possesses only kinetic energy (due to its motion) and no potential energy (as the height to which it is raised from ground level is not changing), the work required to stop the block will be equal to its kinetic energy.