Question

1. It takes a horizontal force 66 N to

keep a 32 kg chair moving uniformly.
Calculate:
a. find the normal force on the chair
b. find μk


2. How much force is required to move
an 1800 N refrigerator uniformly
across the floor if μk = 0.35?

Answer 1

1 a. Fn = Fh = 66 N

Therefore, the normal force on the chair is 32*9.81 N (weight of chair) = 313.92 N.

b. Ff = Fh = 66 N

μk = Ff/Fn = 66/313.92 = 0.210

Therefore, μk is 0.210.

2. Fn = Fg = 1800 N (where Fg is the weight of the refrigerator)

Ff = μkFn = 0.35*1800 = 630 N

Therefore, a force of 630 N is required to move the refrigerator uniformly across the floor.