Experimentally Determine Coefficient of Static Friction

1. Oct 16, 2007

chrissyinbloom

I need to determine the coefficient of static friction for the following set-up.

M1 = 380.45g
M2 = 74.7g

This is what I know... u=F/mg

What I can't figure out is how to factor in the horizontal and vertical weights.

Can anyone help?

Thanks!

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2. Oct 16, 2007

chrissyinbloom

I should clarify.. those weights are the weights where the system just begins to move.

3. Oct 16, 2007

Staff: Mentor

Hint: What does the tension in the string equal?

4. Oct 16, 2007

chrissyinbloom

OK, the tension for both is the same.. and it is equal to.... M2g I think ?

I'll keep thinking on this..

Thanks

5. Oct 16, 2007

Staff: Mentor

Right. There's a single tension in the string and it equals $M_2g$.

So, what must the friction force equal?

6. Oct 16, 2007

chrissyinbloom

OK, here's what I think... the force must equal the tension (M2g), which is equal to uN.

What is N then? The mass of M1??

7. Oct 16, 2007

Staff: Mentor

Good!

Not the mass but the weight of M1.

8. Oct 16, 2007

chrissyinbloom

Yes, the weight!

Thanks a bunch for your help!