Question

A pencil has a mas of 200 grams. If it is placed one meter above the ground, what would be its kinetic energy upon hitting the ground?

Answer 1

According to the energy conservation law, the final kinetic energy $K$ will be equal to the initial potential energy $U$ :

$$K =U =mgh$$

where $m = 200g = 0.2kg$ is the mass of the pencil, $h = 1m$ is the height, $g = 9.8m/s^2$ is the gravitational acceleration. Thus, obtain:

$$K = 0.2\cdot 9.8\cdot 1 = 1.96J$$

Answer. 1.96J.