Question

Two blocks A and B of masses 1.5kg and 0.5kg respectively are connected by a massless inextensible string passing over a frictionless pulley as shown in the figure. Block A is lifted until block B touches the ground and then block A is released.  The initial height of block A is 80cm when block B  just touches the ground. The maximum height reached by block B from the ground after the block A  falls on the ground is
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Answer 1

Answer:

Let velocity of B and A after collision has magnitude v.

At the time of collision tension =T

Impulse provided by tension =∫Tdt

Consider change of momentum of (B + bullet)

mu−∫Tdt=2mv ……… (i)

Consider change of momentum A

∫Tdt=3mv …………..(ii)

From (i) and (ii),

⟹mu=5mv

⟹v=u/5

Hence, Impulse: ∫Tdt=3mv

⟹3m(u/5)=3mu/5