大一物理題.
A uniform steel rod of length 1.20 m and mass of 6.40 kg has attached to each end a small ball of mass
1.06 kg.The rod is constrained to rotate in a horizontal plane about a vertical axis through its midpoint.
At a certain instant it is observed to be rotating with an angular speed of 39.0 rev/s.Because of axle
friction it comes to rest 32.0 s later.Assume a constant frictional torque.
(a) Find the angular acceleration.
(b) Calculate the retarding torque exerted by axle friction.
(c) Determine the total work done by the axle friction.
(d) Calculate the number of revolutions executed during the 32.0 s.
(e) Now suppose that the frictional torque is known not to be constant.which,if any ,of the quantities abcd or d can still be computed without requiring any additional information?if any exists give its value