Answer to Question #110511 in Physics for Brekken Mandt

Question

How much work must be put into a machine that is 70.0% efficient in order to move a mass of 400.0 kg a distance of 12.5 m?

Answer 1

$$\eta W=mgh$$

$$0.7W=(400)(9.8)(12.5)$$

$$W=70000\ J=70.0\ kJ$$