How many revolutions does the object make during the first 2.9s ?
http://session.masteringphysics.com/problemAsset/1…
I’m so confused! Please help!
2 Answers

For the first two seconds the angular velocity ω is 20 rad/s so it turns through 20 x 2 = 40 radians.
Thereafter the angular velocity is 10 rad/s so in the next 0.9s it will turn through 10 x 0.9 = 9 radians
So. in total over the 2.9s it will have turned through 49 radians
To convert this to revolutions as required by the question, remember that 1 revolution is 2π radians
so revolutions = 49 radians / 2π radians per rev
= 7.8 revolutions

What is the particle’s angular velocity at t = 7 s?