rotational

a uniform rod AB of mass m n length l is at rest on a smooth horizontal surface. an impulse J is applied to the end B perpendicular to the rod in horizontal direction . speed of partical at a dist. l/6 frm the centre towards A of the rod after time t=Ï€ml/12J is.
1.2J/m
2.j/√2m
3.J/m
4.√2J/m

2 Answers

106
Asish Mahapatra ·

J = mVcm ... (i)
Jl/2 = ml2/12*ω ... (ii)
==> ω = 6J/ml and Vcm =J/m

at t=Ï€ml/12J,
θ = ωt = π/2

So the rod is perpendicular at that moment wrt initial condition.

So,
v = √(J/m)2 + (J/m)2
= √2*J/m

1
maydayhay ·

velocity of particle = √Vcm2 + (wr)2 + 2Vcm*wr*cosθ

where θ is angle between Vcm and wr....

Here finally, wr and Vcm are perpendicular

Hence speed = √Vcm2 + (wr)2

Vcm = J/m and wr = 6J/ml*l/6 = J/m

put the values and get the answer

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