Friction Practice Problems

Front

What is the coefficient of kinetic friction?

Back

The coefficient of kinetic friction (μk) is a dimensionless value that represents the ratio of the force of kinetic friction between two bodies to the normal force pressing them together. It quantifies how much frictional force opposes the motion of an object sliding over a surface.

Front

How do you calculate the force of friction?

Back

The force of friction (F_friction) can be calculated using the formula: F_friction = μk * N, where μk is the coefficient of kinetic friction and N is the normal force.

Front

What is static friction?

Back

Static friction is the frictional force that prevents two surfaces from sliding past each other. It acts on an object at rest and must be overcome to start the motion.

Front

How do you calculate the force required to start moving an object?

Back

To calculate the force required to start moving an object, use the formula: F_required = μs * N, where μs is the coefficient of static friction and N is the normal force.

Front

What is the difference between static and kinetic friction?

Back

Static friction acts on objects at rest and prevents motion, while kinetic friction acts on objects in motion and opposes their movement.

Front

If a 15.7 kg object is at rest and the coefficient of static friction is 0.33, what is the force required to start moving it?

Back

F_required = μs * N = 0.33 * (15.7 kg * 9.81 m/s²) = 50.8 N.

Front

What is the normal force acting on an object on a level surface?

Back

The normal force (N) is the force exerted by a surface to support the weight of an object resting on it, acting perpendicular to the surface. On a level surface, N = weight of the object.

Front

How does the angle of applied force affect the force of friction?

Back

The angle of the applied force affects the normal force. A force applied at an angle reduces the normal force, which in turn reduces the frictional force, as friction depends on the normal force.

Front

What is the formula for calculating the coefficient of kinetic friction?

Back

The coefficient of kinetic friction (μk) can be calculated using the formula: μk = F_friction / N, where F_friction is the force of friction and N is the normal force.

Front

If a force of 27.2 N is applied at a 22.3 degree angle to pull a 7.412 kg object at constant velocity, how do you find the coefficient of kinetic friction?

Back

First, resolve the applied force into horizontal and vertical components. Then, calculate the normal force and use the formula: μk = F_friction / N.