Answer to Question #301973 in Physics for Luffy

Question

1. A force 16 N pushes the 2 blocks (m1 = 3kg and m2 = 5 kg) in a horizontal surface but doesn’t move. What is the static coefficient friction of the blocks?

Answer 1

By definition, the static friction force is equal to the pushing force $F_{fr} = F = 16N$. On the other hand,

$$F_{fr} = \mu N$$

where $\mu$ is the static friction coefficient, and $N = mg = (3kg+ 5kg)\cdot 9.8 = 78.4N$ is the normal reaction. Thus, obtain:

$$\mu = \dfrac{F}{N} = \dfrac{16N}{78.4N} \approx 0.2$$

Answer. 0.2.