# Homework Help: HELP I NEED HELP FAST Rotational Kinematics

1. Nov 15, 2009

### BlakeEdwards

HELP I NEED HELP FAST!!! Rotational Kinematics

1. The problem statement, all variables and given/known data

A rolling 5 kg wheel with a radius of 5 meters is moving at -50 rad/s as it begins to roll up a hill. It does not slip! When its angular velocity reaches 18 rad/s its angular displacement is -21 radians.
(a) What was its displacement? 105m
(b) What was its angular acceleration? 51.8 rad/s2
(c) What distance did the wheel travel during this observation? 3m

I got a and b but dont understnad what part C is even asking....I think its the same as part a!! can someone HELP!! Much appreciated and explain also....

2. Nov 15, 2009

### ideasrule

Re: HELP I NEED HELP FAST!!! Rotational Kinematics

Are you sure those are the questions and answers as written in the textbook, word by word? If so, I'd agree that c) seems to be asking the same thing as a).

3. Nov 15, 2009

### BlakeEdwards

Re: HELP I NEED HELP FAST!!! Rotational Kinematics

its the exact question

4. Nov 15, 2009

### BlakeEdwards

Re: HELP I NEED HELP FAST!!! Rotational Kinematics

Three masses are arranged on a 81 gram uniform wooden meterstick. 150 grams at the 25 cm mark. 500 grams at the 60 cm mark. 150 grams at the 90 cm mark.

(c) , how much mass sould be added at the 5 cm mark to shift the center of mass to the 50 cm mark?

i got 161.11 grams but it says its wrong....why??????

5. Nov 15, 2009

### ideasrule

Re: HELP I NEED HELP FAST!!! Rotational Kinematics

Well, how did you do the question?