(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The two blocks, m1 = 3.3 kg and m2 = 4.2, in the figure below are connected by a massless rope that passes over a pulley. The pulley is 12 cm in diameter and has a mass of 2.0 kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.35 Nm. If the blocks are released from rest, how long does it take the 4.2 kg block to reach the floor from a height of h = 1.0 m?

2. Relevant equations

torque= r * F

sum of torques = moment of inertia * angular acceleartion

angular acceleration * radius = acceleration

x=v0t + 1/2 a t^2

3. The attempt at a solution

I tried summing torques, saying that m2 is on the left and has torque m2*g*radius. Following this, m1 acts opposite, so subtract m1*g*radius. Friction acts opposite of motion, so acts the direction of m1. So (m2*g*r) - (m1*g*r) - torque(friction) = alpha * 1/2m*r^2 (m is mass of pulley, r is .06m, m1 = 3.3, m2=4.2)

from here, i used alpha*r=a to find linear acceleration

then i used x=v0t + 1/2at^2 to find time, v0 is 0 cuz it starts at rest, a is what i found before

Any suggestions?

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# Homework Help: Two Blocks, Massless Rope. Pulley

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