Q. 424.8( 12 Votes )
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 m/s2)
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
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