Question

When a cricket ball is thrown vertically upwards, it reaches a maximum height of 5 metres. 

(a) What was the initial speed of the ball ? 

(b) How much time is taken by the ball to reach the highest point ? (g=10 ms² )

Answer 1

Initial velocity, u=?

Final velocity, v=0

Acceleration due to gravity, g=-10m/s²

Height, h=5 m

(a) For a freely falling body:

v² = u² + 2gh

(0)² = u² + 2 x(-10)x 5

0= u² -100

u² = 100

So, u=10m/s

(b) Using relation, v=u + gt

0 = 10 + (-10) t

-10= -10 t

t=1sec