# Static Friction Question — A wood block sliding on a tabletop

• physicsstudent111

#### physicsstudent111

Homework Statement
A 4.0 kg block of wood (m 1 ) sits on a level table. A string is tied to the wood and runs over a
frictionless pulley to a hanging object (as shown below). The greatest mass that can be hung
from the string (m 2 ) without moving the block of wood is 1.8 kg. Calculate the coefficient of
static frictions between the block of wood and the table.
Relevant Equations
F=uFn
Fg=Fn
I have no idea how to start this other than that I think that Fn is 17.64N and Fnet is 0. But I don't have the mew, so I am not sure how I am going to get the force of static friction.

Welcome!

About a week. Do you have any suggestions for this question?

About a week. Do you have any suggestions for this question?
Draw a free body diagram (FBD) for the block. They are the cat's mew for problems of this kind.

• bob012345, berkeman and Lnewqban
What is Fn in that equation?
Show us how did you estimate that value of 17.64 N, please.

I assumed that Force of gravity is equal to Fn. So I did 1.8kg(9.80m/s(down))=17.64N. But I think this is wrong

Yes, you have calculated the weight of block #2, but that one is hanging in the air (no friction there). • jbriggs444