Question

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Sample Problem 3. A cricket ball is dropped from a height of 20 metres.
(a) Calculate the speed of the ball when it hits the ground.
(b) Calculate the time it takes to fall through this height. (8 = 10 m/s2)
Solution. (a) Here, Initial speed, u = 0
Final speed, v = ?
(To be calculated)
Acceleration due to gravity, g = 10 m/s2
(Ball comes down)
And, Height, h = 20 m
Now, we know that for a freely falling body:
P = u? + 2gh
So,
12 = (0)2 + 2 x 10 x 20
v2 = 400
v= 1400
v = 20 m/s
Thus, the speed of cricket ball when it hits the ground will be 20 metres per second.
(b) Now, Initial speed, u = 0
Final speed, v = 20 m/s (Calculated above)
Acceleration due to gravity, 8 = 10 m/s2
And,
Time, t = ?
(To be calculated)
Putting these values in the formula:
v = u + gt,
we get :
20 = 0 + 10 x
10 t = 20
20
10
t = 2 s
Thus, the ball takes 2 seconds to fall through a height of 20 metres.
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Answer 1

Answer:

Such a big question

Where did you get it from