InterviewSolution
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InterviewSolution
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Three identical balls, ball I, ball II and ball III are placed on a smooth floor on a straight line at the separation of `10m` between balls as shown in figure. Initially balls are stationary. But I is given velocity of `10m//s` towards ball II, collision between balls I and II is inelastic with coefficient of restitution `0.5` but collision between balls II and III is perfectly elastic. What is the time interval between two consecutive collisions between ball I and II? |
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Answer» Let velocity of Ist ball and Iind ball after collision be `v_(1)` and `v_(2)` `v_(2) -v_(1) = 0.5 xx 10` ...............(i) `mv_(2) + m_(1)v_(1) = m xx 10` .......................(ii) `rArr v_(2) + v_(1) = 10` Solving Eqs. (i) and (ii) `v_(1) = 2.5 ms^(-1)`, `v_(2) = 7.5 ms^(-1)` Ball II after moving 10 m collides with ball III elastically and stops. But ball I moves towards ball II. Time taken between two consecutive collisions. `(10/7.5) + (10 - 10 xx (2.5)/(7.5))/(2.5) = 4s` |
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