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**1. Homework Statement**

A solid door of mass M = 19 kg and width = 128 cm is hit at a right angle by a mud ball of mass m = 0.6 kg, which, as Fig. 10–44 shows, hits the door at the edge with speed v = 16 m/s and sticks.

Figure 10-44

(a) What is the rotational inertia of the door about the hinges?

10.377 kg·m2

(b) What is the angular velocity of the door after having been struck?

________ rad/s

(c) What fraction of the initial energy does the moving door–mud ball system retain?

_______

**2. Homework Equations**

p=mv

I= 1/3mr^2

L=mvr

**3. The Attempt at a Solution**

-Part A was simply 1/3mr^2

-Part B confuses me because I have to somehow make a linear momentum into a rotational momentum, while not forgetting the moments of inertia. Someone please shed some insight to this simple problem.

-Part C = I need part B :/