3pls try neone.
A horizontal plank having mass m lies on a smooth horizontal surface.A sphere of same mass and radius r is spined to an angular frequency w0 and gently placed on the plank as shown in the figure.If coefficient of friction between the plank and the sphere is μ.Find he distance moved by the plank till the sphere starts pure rolling on the plank.The plank is long enuf.
i thot the frictional force will get adjusted in order to attain the rolling motion so we wont have uniformly accelerated motion,
but i have a seen a similar type pbm in resnick there they have said dat we have only the uniformly accelerated motion.
Can u pls help me out there.
And can we conserve ang.momentum abt the pt of contact.
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2 Answers
106Initially,
So initially, the sphere will undergo uniformly accelerated motion and with decreasing angular velocity
the plank will move backwards with uniform acceleration
till the velocity of point of contact of the sphere on the plank wrt the plank is zero.
U should be able to proceed further
U cant conserve angular momentum abt point of contact because there is frictional work in this case and the point of contact does not have zero velocity. ie. Vcom≠0 initially