Question

Sorin hits a cricket ball straight up into the air. After 1.5s, the ball is falling straight down with a speed of 6.5 m/s. We want to find the initial vertical velocity of the ball. We can ignore air resistance. Which kinematic formula would be most useful to solve for the target unknown?

Answer 1

Explanation:

We have, Sorin hits a cricket ball straight up into the air. After 1.5 s, the ball is falling straight down with a speed of 6.5 m/s.

We want to find the initial vertical velocity of the ball.

The relation between initial speed, final speed, acceleration and time is given by using first equation of kinematics. Let v₀ is the initial speed. So,

`v=v_o +at`

Here, v = -6.5 m/s, t = 1.5 s and a = -g

`v_o=v-at\\\\v_o=v+gt\\\\v_o=-6.5+9.8* 1.5\\\\v_o=8.2\ m/s`

So, the initial velocity of the ball is 8.2 m/s and the formula used is (1).