Question

5. The body, weighing 200 kg, falls freely from a height of 1000 m. Find its kinetic energy and potential 12 seconds after the start of free fall.

Answer 1

In 12 seconds, the body will achieve a speed of

$$v=gt=117.6\text{ m/s}.$$

Meanwhile it moved down for

$$h=\frac{gt^2}{2}=705.6\text{ m}.$$

It is

$$H=y-h=1000-705.6=294.4\text{ m}.$$

The kinetic and potential energy:

$$E_K=\frac12mv^2=1.383·10^6\text{ J}.\\\space\\ E_P=mgH=577000\text{ J}.$$