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A ball moving with a velocity `v` hits a massive wall moving towards the ball with a velocity a. An elastic impact lasts for time `/_ `A. b, cB. a, dC. b, dD. c, d |
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Answer» Correct Answer - A Velocity of ball after collision is `V_("bal")~=-(v+2u)and v_("wall")~=u` Since, `F_("ball")=((Deltap)/(Deltat))_("ball")=(-m(v+2u)-mv)/(Deltat)` `rArr" "F_("ball")=(-2m(v+u))/(Deltat)rArr|F_("ball")|=(2m(v+u))/(Deltat)` Increase in K.E. of ball is given by `DeltaK=(1)/(2)m(v+2u)^(2)-(1)/(2)mv^(2), DeltaK=2 m u(u+v)` |
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