Imagine a three-step pulley with a string wrapped around it, connected to a mass
ID: 2261666 • Letter: I
Question
Imagine a three-step pulley with a string wrapped around it, connected to a mass which hangs freely. As the hanging mass is released, the string unwinds, and the pulley spins.
a) Construct an expression for the net force on the hanging mass in terms of mh (mass of hanging mass), g, T, and a.
b) Develop an expression that relates the torque on the pulley to the tension. Assume that the angle between the string and the pulley is 90 degrees.
c) Using these two equations, find an expression for the troque on the pulley in terms of Rp (radius of the pulley), mh, g, and a
Explanation / Answer
a)
Fnet = mh*g - T
mh*a = mh*g - T
==> T = mh*g - mh*a
b) torque, Torque = r*T*sin(90)
Toruqe = Rp*T
Rp---> radius of the pulley
c)
Torque = Rp*(mh*g-m*a)