Question

A crate of 37.2-kg tools rests on a horizontal floor. You exert a gradually increasing horizontal push on it and observe that the crate just begins to move when your force exceeds 322 N . After that you must reduce your push to 240 N to keep it moving at a steady 29.1 cm/s .

A.What is the coefficient of static friction between the crate and the floor?

B.What push must you exert to give it an acceleration of 1.11 m/s2 ?

C.What is the coefficient of kinetic friction between the crate and the floor?

D.Suppose you were performing the same experiment on this crate but were doing it on the moon instead, where the acceleration due to gravity is 1.62 m/s2. What magnitude push would cause it to move?

E. What would its acceleration be if you maintained the push in part B?

Answer 1

A )

240 = $\mu$ _s X 37.2 X 9.8

$\mu$ _s = 0.65

B )

( F – $\mu$ ) X 37.2 X 9.8 = 37.2 X 1.11

( F – $\mu$ ) = 0.11

C)

240 = $\mu$ _k X 37.2 X 9.8

$\mu$ _k = 0.65

D )

( F – $\mu$ ) X 37.2 X 1.62 = 37.2 X 1.11

( F – $\mu$ ) = 0.68

E )

240 = $\mu$ _k X 37.2 X 1.62

$\mu$ _k = 3.98