Examples on Static Friction

Example 1: Determine the static friction acting on a couch of 7 kg, given the force applied, is 45 N and the coefficient of friction is 0.6. (Take g = 9.8 m/s²)

Solution:

Given: 

Weight of Couch = 7 kg

g = 9.8 m/s²

F_n = 7 × 9.8 N

    = 68.6 N

μ_s = 0.6

Since, F_s = μ_s × F_n

= 0.6 x 68.6 N

= 41.16 N

Thus, the friction force applied is 41.16 N

Example 2: Determine the static friction acting on a table of 10 kg, given the force applied, is 200 N and the coefficient of friction is 0.7. (Take g = 9.8 m/s2)

Solution:

Given: 

Weight of Table = 10 kg

g = 9.8 m/s²

F_n = 10 × 9.8 N

    = 98 N

μ_s = 0.7

Since, F_s = μ_s × F_n

= 0.7 x 98 N

= 68.6 N

Thus, the friction force applied is 68.6 N

Example 3: Find the coefficient of static friction if an object is being pushed from a state of rest by applying a force of 500 N and the static friction acting on it is 250 N.

Solution:

Given: 

F_s = 250 N and F_n = 500

Since, F_s = μ_s × F_n

250 = μ_s x 500

μ_s = 250/500

μ_s = 0.5

Example 4: Determine the static friction acting on an object of mass 50 Kg, given the force applied, is 1000 N and the coefficient of friction is 0.4.

Solution:

Given: 

Weight of Object = 50 kg

g = 9.8 m/s²

F_n = 50 × 9.8 N

    = 490 N

μ_s = 0.4

Since, F_s = μ_s × F_n

= 0.4 x 490 N

= 196 N

Thus, the friction force applied is 196 N

Friction is a force that prevents some sliding objects from moving. We can find friction in our surroundings at any time. It acts in a direction opposite to that of the object’s movement. We can stop quickly if we run down the sidewalk and slow down and then eventually stop because of the frictional force between our footwear and the ground. Friction can occur with either a moving or stationary body. As a result, it can be both dynamic and static.