- #1

jakec

- 5

- 0

## Homework Statement

To lower himself from a balcony an 80kg stuntman grabs a rope connected to a 400kg cylinder with a 1.2m diameter that is free to rotate about its axis of symmetry. What is the stuntman's acceleration as he falls?

## Homework Equations

I missed this on a homework assignment. I know the correct answer is 2.86m/s

^{2}but I can't find what I did wrong.

## The Attempt at a Solution

moment of inertia for a cylinder: I=1/2 Mr

^{2}

radius of cylinder = 0.6m

torque applied by stuntman = mgr = 80kg * 9.8m/s

^{2}* 0.6m = 470.4Nm

Using t = Iα

470.4Nm = (0.5 * 400kg * 0.6m

^{2})α

α = 470.4Nm / (0.5 * 400kg * 0.6m

^{2}) = 6.53rad/s

^{2}

a = αr = 6.53rad/s

^{2}* 0.6m = 3.92m/s

^{2}

What am I missing?