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Grade 12th passMechanics

Blocks P and R from rest and moves to the right with acceleration aP = 12t m/s^2 ans aR = 3m/s^2 Here t is seconds. The time when block Q again comes to rest is(1) 1s(2) 3/2 s(3) 2s(4) 1/2s

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Profile image of Vikash Kumar Singh
8 Years agoGrade 12th pass
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2 Answers

Profile image of Ishika Joshi
8 Years ago
Here, to ensure that the block Q is at rest, we will find the relation between the velocities of the blocks using the constraint concept.We arrive to a relation:V(p)-V(r)-V(q)=0...(i)We know, v(p)=6t^2, v(r)=3t (integrating the given values) We want v(q)=0Therefore, using eqn(i),6t^2=3tt=1/2
Profile image of Balkaran Singh
6 Years ago
Ap=12t 
Vp=integration Vp=12t^2/2=6t^2
Integration Vr=3=3t
6t^2×T-3t×T-2T×v=0
6t^2=3t................
t=1/2 sec