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15/09/2021 10:40 am
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A ball of mass 0.15 kg is dropped from a height 10 m, strikes the ground and rebounds to the same height. The magnitude of impulse imparted to the ball is (g = 10 m/s2) nearly :
(1) 0 kg m/s
(2) 4.2 kg m/s
(3) 2.1 kg m/s
(4) 1.4 kg m/s
1 Answer
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15/09/2021 10:50 am
Correct answer: (2) 4.2 kg m/s
Explanation:
Velocity just before striking the ground
v1 = \(\sqrt{2gh}\)
v1 = \(\sqrt{2(10)(10)}\) = 10√2 m/s
v1 = -10√2 j
If it reaches the same height, speed remains same after collision only the direction changes.
v2 = 10√2 m/s
\(\bar{v_2} = 10\sqrt 2 \hat{j}\)
|Impulse| = \(m|Δ \vec{v}|\)
= m|10√2 j - (-10√2 j)|
= 0.15[2(10√2)]
= 3√2 kg m/s
= 4.2 kg m/s