# Angular Speed question

1. May 5, 2012

### netone

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

. The angular speed of an automobile engine is increased at a constant rate from 140 rad/s to
200 rad/s in 20 s. The number of radians through which the engine turns during this 20-s
interval is

2. Relevant equations

3. The attempt at a solution
I didnt know where to begin with this question, or know of an equation to start with. so a general hint in the right direction would be very appreciated.

2. May 5, 2012

### Staff: Mentor

What's the average speed over the 20 seconds?

3. May 5, 2012

### netone

Last edited: May 5, 2012
4. May 5, 2012

### Staff: Mentor

That's not the average angular speed. That's the average angular acceleration. What's the average angular speed?

5. May 5, 2012

6. May 6, 2012

### Staff: Mentor

Sooo, if the average rotational speed is 170 rad/s, and the engine runs for 20 s, how many radians does it rotate through?

7. May 6, 2012

### netone

oh ok ,so it would just be 3400 then. Thanks for your help!