# Calculating Rotational Acceleration of a Wheel

1. Dec 1, 2009

### kfish

1. The problem statement, all variables and given/known data
A rotating wheel requires 3.05 s to rotate through 37.0 revolutions. Its angular speed at the end of the 3.05 s interval is 97.1 rad/s. What is the constant angular acceleration of the wheel?

2. Relevant equations
Well from basic calculus I know that acceleration is equal to (dV/dT) or the derivative of velocity over derivative of time.

That is the only pertinent equation I can think of for this problem.

3. The attempt at a solution

I used the velocity, 97.1 rad/s, and divided it by the time, 3.05s.

According to the online homework this is incorrect. I cannot think of any other way to calculate it since the radius is not given.

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

A racing car travels on a circular track of radius 230 m. Suppose the car moves with a constant linear speed of 53.0 m/s.

(b) Find the magnitude and direction of its acceleration.

Part (a) had me calculate the velocity which came out to 0.23 rad/s. The velocity is correct.

2. Relevant equations
a= linear acceleration
A=rotational acceleration

A=a/R

circumference = 2piR

3. The attempt at a solution

I figured since it says a constant linear acceleration then the angular acceleration=0 because A=(0)/(230) = 0. This answer is incorrect according to the online homework. I'm not sure what else to do.

Last edited: Dec 1, 2009
2. Dec 1, 2009

### Kurdt

Staff Emeritus