1. It takes a 25 N force to push a 250 N box across the floor.

a. How much work is done against friction when the box is moved 2 m across the floor?

b. How much work is done against gravity when the box is lifted 2 m above the floor?

A: - 50 J

B: - 500 J

Explanation:

a) Given that a 25 N force is applied to move the box. Also the floor is having friction surface.

So in order to move the box, the floor should have friction of atleast 25 N.

∴ friction = 25 N

Work done = force * displacement of box

Given, the box is moved 2 m across the floor

So, Work done = friction * 2 m

= 25 * 2

= 50 J

b) Given, the box is having weight of 250 N weight

Gravitational force is acting on the box which is equal to (mass * gravity)

∴ Force = 250 N

The box is lifted 2 m above the floor.

So, displacement = 2 m

Work done = force * displacement of box

Work done = 250 * 2

= 500 J