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a marble of 100g dropped from the top of a tower of height 5m and comes to rest when it hits the ground the change in momentum of thr marbel in kg ms is?? |
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Answer» mass, m = 1kgheight, s = 20minitial velocity of ball, u = 0m/sacceleration, a = 10m/s 2 Using, v 2 = u 2 + 2as = 0 + 2×10 ×20 = 400 v = 20m/sNow, let us take upward direction as positive and downward direction as negative.Initial momentum of the ball (before STRIKING the GROUND) = m×v = 1×(-20) (velocity is downward, hence negative) = -20kgm/s Now, when the ball strikes and rebounds, its velocity BECOMES +20m/s (after striking, it moves upward, hence positive velocity)Final momentum (after striking the ground) = m×v = 1×(+20) = +20kgm/sChange in momentum = Final momentum - Initial momentum = 20kgm/s - (-20kgm/s) = 40kgm/s i |
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