a) At the bottom is a 3 step pulley; consisting ofthree wheels of different diam
ID: 1700541 • Letter: A
Question
a) At the bottom is a 3 step pulley; consisting ofthree wheels of different diameters.b) The rotating arm has two masses attached,and is screwed into the 3 step pulley. Whenthe pulley rotates, so does the rod.c) The string is wrapped around one of thewheels in the 3 step pulley and passes overthe smart pulley. The mass hanger ishooked into the loop at the end of the string.d) When the system is released, the mass hanger falls, turning the smart pulley, and the 3 step pulley withthe rod attached.e) Assume: that the smart pulley is very light, so its moment of inertia is negligible as compared to themoment of inertia of the 3 step pulley and rod.
if you increase m, the mass on the mass holder, what happens to the following quantities:
- , the angular accelertion of the pulley.
- I, the angular momentum of the pulleys-plus-rod system.
if you move the two masses attached to the rotating rod away from the center of mass of the rod, what happens to the following quantities:
- , the angular accelertion of the pulley.
- I, the angular momentum of the pulleys-plus-rod system.
Explanation / Answer
a) Since the torque on the smart pulley increases (due to increase in mass m) both angular acceleration and angular momentum must increase for a given I, the moment of inertia of pullley and rod. Let a = angular acceleration w = angular velocity of 3 step pulley T = torque on 3 step pulley b) moving the masses outward on the rod increases I For a given torque (m remains constant) T = I a After a time t then T * t = I a t = I w For a fixed torque the product of I and w is constant so the angular momentum remains constant even tho a decreases due to the increase in I
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