Question

A painter drops a 1.5kg can o paint from a height of 9m . Determine (i) The kinetic energy of the can when it is at a height is at a height of 4m. (ii) The speed at which the can hits the ground

Answer 1

(i) The kinetic energy of the can when it is at a height of 4m. First, find the work done by gravity:

$$E_K=W=mg\Delta h=73.5\text{ J}.$$

(ii) The speed at which the can hits the ground:

$$mgh=\frac12 mv^2,\\\space\\ v=\sqrt{2gh}=13.3\text{ m/s}.$$