# Help with something to do with angular stuff?

1. Jan 16, 2008

A copper block rests 39.0 cm from the center of a steel turntable. The coefficient of static friction between the block and the surface is 0.34. The turntable starts from rest and rotates with a constant angular acceleration of 0.50 rad/s2. After what time interval will the block start to slip on the turntable? (Hint: The normal force in this case equals the weight of the block.)

I seriously have no idea which formulas to use...Thanks!

Solved...thanks

Last edited: Jan 16, 2008
2. Jan 16, 2008

### HallsofIvy

Staff Emeritus
Do you know how to calculate the centrifugal force on a rotating object?

3. Jan 16, 2008

I only know how to do centripetal forces...

Actually hold on...maybe

4. Jan 16, 2008

I have down the formula:

force that maintains circular motion=mrw^2

If there was a way to find angular displacement, that would be helpful.

5. Jan 16, 2008

### foxjwill

If you're trying to confuse the poor lad, that's not very nice. Centrifugal force, as I'm sure you know, is a fictional force, which means, for the purposes of this thread, that it doesn't exist.

6. Jan 16, 2008

### foxjwill

Try doing a force body diagram.

7. Jan 16, 2008