Question

Calculate the Kinetic friction, given the following,

kinetic friction formula: f_k = U_k n

Torque: 1016.86 Nm

Force= 225lbs

Distance= 40 inches

Uk= 0.57

This is the only information I have, not sure If i need any other parameters to calculate the static friction. If so please let me know

Answer 1

This is one of those where you have to combine a couple of different formulas to get your answer.

You have the correct formula for friction force fk:
fk = ?kN

...which you can rearrange to:
?k = fk/N

The bad news is, you don't know the values of "fk" or "N".
The good news is, you do have a FORMULA for "N", plus an additional formula for "fk"

The formula for "N" is (in this case):
N = weight = mg

For "fk", notice that the friction force is the NET FORCE acting on the disk. That means it obeys Newton's 2nd Law of Motion:
fk = net force = ma

So now you can substitute these formulas into your "?k" formula:

?k = fk/N = (mg)/(ma)

The "m"'s cancel out:

?k = g/a

You know that g = 9.8meters/sec