Question

How much work is done by a person who picks up a 3-kg crate from the floor, raises it 2m and sends it flying with a speed of 4m/s?

Answer 1

Given:

Mass of the crate = 3 kg

Height to which the crate is raised = 2m

Velocity at which the crate is thrown = 4 m/s

To find:

The work done by the person.

Solution:

Total work done = work done in raising the potential energy of the crate + kinetic energy spent in throwing the crate

Work done in raising the potential energy = m*g*h

= 3*10*2 = 60 J

Kinetic energy spent = 1/2mv²

= 1/2 * 3 * (4)² = 24 J

Total work = 60 J + 24 J = 84 J

Therefore, work done is 84 J.