If a block positioned on an incline is not moving then the f

If a block, positioned on an incline is not moving, then the force of friction is Fa = mu s N. Fill-in-the-blank 1. The frictional force acts____ to the contacting surfaces in a direction____ to the motion or tendency for motion of one surface relative to another. 2. ______is a force that resists movement of two surfaces in contact that might slide relative to one another. Matching (a) Coefficient of static friction (b) Coefficient of kinetic forum Short Answer 3. Using any resource other than a friend, determine the average coefficient of kinetic friction for steel on steel (unlubricated). (Identify your resource!) 4. If the coefficient of static friction at the contact points A and B is mus = 0.25, determine the maximum force P that can be applied without miming the 50 kg spool to move (Draw the FBD first!)

Solution

1) Parallel, opposite

2) Friction

3) muk is for kinetic while mus is for static

4) mus = 0.25

mu = Ff/Fn i.e 0.25 = Ff/50

Or Ff = 50(0.25) = 12.25

P = 12.25 newtons

Steel on Steel

0.74

0.57