Question

A block of mass $m$ is sliding on a smooth floor with a velocity $v$. The minimum amount of work required to stop it is (assume the block is at ground level):

• A. equal to the potential energy of the block
• B. greater than the potential energy of the block
• C. equal to the kinetic energy of the block
• D. greater than the kinetic energy of the block

Answer 1

The correct option is C equal to the kinetic energy of the block

The work done to stop the block would need be opposite to the direction of motion, so as to stop the moving block. Since the body possesses only kinetic energy (due to its motion) and no potential energy (as it is at ground level), the minimum work required to stop the block will be equal to its kinetic energy.