Question

Of the blocks listed below, which combination of materials will have the highest resistance to sliding?

Block Weight Friction
A 150 lb 30 lb
B 20 N 5 N
C 1,500 lb 60 lb
C
A
B

Answer 1

You compare the coefficient of friction μ = (friction force)/(normal weight) for each block.

- A: μ = 30 lb / 150 lb = 0.20
- B: μ = 5 N / 20 N = 0.25
- C: μ = 60 lb / 1500 lb = 0.04

So the resistance to sliding is highest for B, then A, then C (B > A > C).