Marisol pushes a 3.0 kg box 7.0 m across the floor with a force of 12 N. She lifts the box to a shelf 1 m above the ground. How much work does Marisol do on the box?

Work = (force) x (distance)

- - Floor portion:

Force = 12 N

Distance = 7.0 m

Work = (12 x 7) = 21 joules

- - Lift portion:

Weight of the box = (mass) x (gravity) = (3.0) x (9.8) = 29.4 newtons

Force to lift = weight of box = 29.4 N

Distance = 1 m

Work = (29.4 x 1) = 29.4 joules

Total work on the box = (21 + 29.4) = 50.4 joules