Question

1. A winch lifted a mass of 2500 kg through a height of 22 m in 15 s. Calculate the power in
hp.

2. A 50 kg is raised vertically 8 m. What is the potential energy?

Answer 1

1. The power is (by definition):

$$P = Fv$$

where $F = mg$ is the gravity force against which the winch lifted a mass, $v = h/t$ is the speed of this mass ($h =22m, t=15s$ ). Thus, obtain:

$$P = \dfrac{mgh}{t} = \dfrac{2500\cdot9.81\cdot 22}{15} = 35970\space W$$

In order to convert it to hp, one should multiply it by 0.00134:

$$P = 35970\cdot0.00134 \approx 48.2\space hp$$

2. The potential energy can be caculated with the following formula:

$$U = mgh = 50kg\cdot 9.81 m/s^2\cdot 8m = 3924J$$

Answer. 1) 48.2 hp, 2) 3924 J.