What torque would have to be applied to a rod with a length of 4 m and a mass of 3 kg to change its horizontal spin by a frequency of 12 Hz over 1 s?

1 Answer
Jane
Jan 27, 2018

Torque (tau) is defined as change in rate of angular momentum (L)i.e (dL)/dt i.e (d(Iomega))/dt i.e I (domega)/dt (where, Inis the moment of inertia)

Now,moment of inertia of a rod w.r.t its one end along an axis perpendicular to its plane is (ML^2)/3 i.e 3*(4)^2/3 or 16 Kg.m^2

Now, rate of change in angular velocity = (domega)/dt = 2pi (nu1-nu2)/t i.e 2 pi*12/1 or 24 pi

So, tau = 16* 24 pi or, 1206.37 N.m

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