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!