Friction

What is frictional force?

• A force that always acts to accelerate objects.

• A force that opposes the relative motion between two surfaces in contact.

• A force that is only present when an object is at rest.

• A force that increases the velocity of moving objects.

What is the coefficient of static friction?

• The ratio of the limiting friction to the normal force.

• The force required to keep an object moving.

• The angle at which an object starts to slide.

• The speed at which an object moves across a surface.

What does the angle of repose represent?

• The maximum angle at which an object can rest on a slope without sliding.

• The angle between the normal force and frictional force.

• The coefficient of static friction for a given surface.

• The minimum angle at which an object starts to move.

What is the normal force?

• The force that acts parallel to the surface.

• The force that acts perpendicular to the surface of contact.

• The force of gravity acting on an object.

• The force that opposes gravity.

What is static friction?

• The friction that acts on moving objects.

• The friction between two objects that are not moving relative to each other.

• The friction that only acts when an object is sliding.

• The friction that decreases as the speed of an object increases.

What is limiting friction?

• The maximum frictional force that must be overcome before an object starts to move.

• The minimum frictional force that acts on an object in motion.

• The frictional force that increases with speed.

• The frictional force that is independent of the object's surface area.

How does mass affect the frictional force between two surfaces?

• Increasing mass decreases frictional force.

• Mass has no effect on frictional force.

• Increasing mass increases the normal force, which can increase frictional force.

• Mass directly increases frictional force without affecting the normal force.

What happens to the coefficient of static friction if the surfaces in contact become smoother?

• It increases.

• It decreases.

• It remains the same.

• It becomes zero.

Which of the following is true about the angle of repose?

• It decreases with an increase in the coefficient of static friction.

• It increases with an increase in the coefficient of static friction.

• It is independent of the coefficient of static friction.

• It is always less than 45 degrees.

What role does the normal force play in the calculation of frictional force?

• It is directly proportional to the frictional force.

• It is inversely proportional to the frictional force.

• It has no role in the calculation of frictional force.

• It decreases the frictional force.