A block of mass 4 kg, which has an initialspeed of 3 m/s at timet = 0, slides on ahorizontal surface. Find the magnitude of the work that mustbe done on the block to bring it to rest?

18 J

Explanation:

Work done: This can be defined as the product of force and distance acting on a body. The S. I unit of work is Joules (J)

From the question, the work that must be done in bringing the block to rest is equal to the kinetic energy of the block.

Ek = 1/2mv² ... Equation 1

Where Ek = kinetic eenrgy m = mass of the block, v = velocity of the block.

Given: m = 4 kg, v = 3 m/s.

Substituting into equation 1

Ek = 1/2 (4) (3²)

Ek = 2 (9)

Ek = 18 J.

Thus the work that must me done on the block to bring it to rest = 18 J.