Question

Einstein throws a ball from the ground to the top of the goal. If it returns to the ground after 7 seconds, what is the height of the goal?

Answer 1

The ball starts falling from the top of the goal with zero initial velocity. Thus, the distance travelled by ball (height of the goal) is:

$$h = \dfrac{gt^2}{2}$$

where $g = 9.81m/s^2$ is the gravitational acceleration and $t = 7s$ is the time of falling. Thus, obtain:

$$h = \dfrac{gt^2}{2} = \dfrac{9.81\cdot 7^2}{2} \approx 240.345m$$

Answer. 240.345 m.