Question

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

Answer 1

Answer:

kinetic friction= 165-127= 38N

so 38 = £ mg =£ 25×10

£ = 38/250= 0.152

Answer 2

Given: mass of chair = 25kg

           Horizontal force = 165N

           Force that keep the chair to be moving = 127N

To find The coefficient of kinetic friction and static friction.

Solution:

• Friction is the force that causes the hindrance to the motion of any object. Its direction is opposite to the motion of the body.

The normal force (N) = mg = 25×10 = 250N.

• The coefficient of static friction is the ratio between the maximum amount of static friction force (F) between the surfaces which are in close proximity to each other prior to the commencement of the movement to normal (N) force.

Coefficient of static friction = 127/250 = 0.508

μs = 0.508

• The coefficient of kinetic friction is the ratio of the frictional force between the object and the surface to the normal force acting on the object.

Coefficient of kinetic friction = 165/250 = 0.66

μk = 0.66