Question

At the top of a raised platform, a ball is thrown vertically upward with a speed of 50 m/s. The ball rises up, then falls to the ground below the platform with a downward speed of 100 m/s. For how much time was the ball in free-fall?

Answer 1

Given data:

* The initial velocity of the ball at the peak point is 0 m/s

* The final velocity of the ball is 100 m/s

Solution:

By the kinematic equation,

$v-u=gt$

where v is the final velocity, u is the initial velocity and g is the acceleration due to gravity, and t is the time for which the ball is in free fall,

$\begin{gathered} 100-0=9.8\times t \\ 100=9.8\times t \\ t=\frac{100}{9.8} \\ t=10.2\text{ s} \end{gathered}$

Thus, the ball was in free fall for 10.2 seconds.