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प्रश्न
Exercise Problems.
A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 ms–2, with what velocity will it strike the ground? After what time will it strike the ground?
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उत्तर
Given: height = 20 m
acceleration = 10 ms– 2
Formula: For free falling body,
- v = gt
- s = 1/2 gt2
Solution:
time taken to strike the ground
s = 1/2 gt2
20m = 1/2 × 10 ms – 2 × t2
t2 = `"40m"/"10ms"^(−2)`= 4s 2
∴ t = 2s - Velocity of the ball when it strikes ground v = gt
v = 10ms– 2 × 2s
v = 20ms– 1
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