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

A mass of 20 g is tied to one end of a thin thread. The other end is wrapped around a small cylinder of radius 0.01252 m. The small cylinder is attached to a much heavier aluminum disk. You calculated the rotational inertia of the aluminum disk in a previous problem in this assignment.

a) When the mass falls it causes the small cylinder and the aluminum disk to rotate as discussed. What should the angular acceleration of the system be?

b) Determine the angular speed of the rotating disks after 6.04 seconds if the hanging mass is released from rest?

c) How many radians have the disks rotated after this time?

d) What is the linear speed and kinetic energy of the dropping mass at this time?

2. Relevant equations

KE(linear)=1/2 mv^2

KE(rotational)= 1/2 mv^2 + (1+(I/mv^2))

3. The attempt at a solution

I had gotten the correct answers for a-c (I just put up the questions in case they were pertinent to solving part d). For part d, I figured out the linear velocity through the relationship of v=rw. In trying to solve for KE(linear), I used the above equation. When the question talks about a previous problem, we solved for the moment of inertia for the aluminum disk and were also given its mass. In plugging in the numbers, I did KE=1/2 (mass of weight)*(linear velocity calculated)^2. Is there something wrong in my way of approaching the problem or did I somehow use the wrong equation?

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# Homework Help: Rotational energy

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