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July 25, 2014

July 25, 2014

Posted by **Anonymous** on Thursday, October 18, 2012 at 11:48am.

a) Before it hits the door, does the bullet have angular momentum relative the door’s axis of rotation? Explain.

b) Is mechanical energy conserved in this collision?

c) If the door opens immediately after collision, calculate the angular speed the door swing. The door has the same moment of inertia as a rod with axis at one end.

d) Calculate the energy of the door-bullet system and determine whether it is less or equal to the kinetic energy of the bullet before collision.

- Physics: Rotational Motion -
**Damon**, Thursday, October 18, 2012 at 12:05pmd) Calculate the energy of the door-bullet system and determine whether it is less or equal to the kinetic energy of the bullet before collision.

1. Of course m * R x V = .005 * .9 * 1000

2. No reason it should be, heat generated when bullet strikes. However Angular momentum does not change.

3. I am going to ignore the I of the bullet after collision which is .005*.81

so

.005 * .9 * 1000 = I w = (1/3)18(1)^2 w^2

So w = 0.866 radians/second

- Physics: Rotational Motion -
**Damon**, Thursday, October 18, 2012 at 12:14pmI think you can do (1/2) m v^2 and (1/2) I w^2

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