Question

A 25kg chair initially at rest on a horizontal floor requires 165 N force to set it in motion. Once the chair is in motion, a 127 N horizontal force keeps it moving at a constant velocity. Find the coefficient of static friction between the chair and the floor.

Answer 1

The coefficient of static friction between the chair and the floor is 0.67

Explanation:

Given:

Weight of the chair = 25kg

Force = 165 N (F_applied)

Force = 127 N (F_max)

To find: Coefficient of static friction  

The “coefficient of static friction” between a chair and the floor is defined as the ration of maximum force to the normal force acting on the chair  

μ_s=$F_{max}/F_{n}$  

The F_n is equal to the weight multiplied by its gravity

∴$F_{n}$=mg  

Thus the coefficient of static friction changes as

μ_s=$F_{max}/mg$

μ_{s} = $=165N/((25kg)\times(9.80 m/s^2 ) )$

= 0.67