Sage-Tips

Is there friction if there is no applied force?

Friction always acts to oppose any relative motion between surfaces. For the simple example of a book resting on a flat table, the frictional force is zero. There is no force trying to move the book across the table, so there is no need for a frictional force because there is nothing for the frictional force to oppose.

What is the friction between two stationary objects?

Static friction is the friction that exists between a stationary object and the surface on which it’s resting. Friction in general is a force that makes it harder for two objects to slide alongside one another. On a flat surface, the normal force is equal to the force of gravity acting down on the object.

Is there friction when an object is not moving?

Friction is the force resisting motion between surfaces. There is no requirement that surfaces should already be moving i.e. friction does exist for stationary objects, it is called Static friction.

Can there be frictional force between two surfaces when there is no relative motion between the two give an example to illustrate your answer?

If there is no relative motion between objects in contact, then the friction force (if there is one) is the static force of friction (FS). An example is a box that remains at rest on a ramp.

Can friction be the only force acting on an object?

We’ve learnt that friction is the opposition of motion and that friction appears the instant a force is applied on an object i.e when an object is at rest (with no force acting on it) then there is no frictional force.

Is there friction on a stationary object on a flat surface?

Yes. Friction exists, but does not necessarily exert a force. If an object is at rest on a flat, horizontal surface that is also stationary, there is static friction between the object and the surface.

What kind of friction is called if two object are in contact at rest?

When the two objects are in relative motion we call it kinetic friction. When they are at rest relative to one another, it’s static friction.

What is termed as the friction between two solid object when at rest?

Because the friction thus far described arises between surfaces in relative motion, it is called kinetic friction. Static friction, in contrast, acts between surfaces at rest with respect to each other. The value of static friction varies between zero and the smallest force needed to start motion.

What friction force is acting on a non moving object?

Static friction
Static friction is friction between two objects that are not moving relative to each other. This frictional force is what prevents a parked car from sliding down a hill, for example. Before an object at rest on a surface can move, it must overcome the force of static friction.

Why does friction force exist?

Friction occurs because no surface is perfectly smooth. Rougher surfaces have more friction between them. Heavier objects also have more friction because they press together with greater force. Friction produces heat because it causes the molecules on rubbing surfaces to move faster and have more energy.

Does friction exist if an object is stationary?

Yes. Friction exists, but does not necessarily exert a force. If an object is at rest on a flat, horizontal surface that is also stationary, there is static friction between the object and the surface.

Does friction exist but not exert a force?

Yes. Friction exists, but does not necessarily exert a force. If an object is at rest on a flat, horizontal surface that is also stationary, there is static friction between the object and the surface. But the friction that exists between the two surfaces only exerts a force when there is some other force applied.

Do all surfaces need to be moving to have friction?

There is no requirement that surfaces should already be moving i.e. friction does exist for stationary objects, it is called Static friction. When a force is applied on an object in order to move it, it has to overcome the static friction before the object can be moved.

What causes friction between two objects?

Big Ideas: Friction is caused by collisions between bumps of varying sizes on two surfaces in contact. Static friction occurs when a force is applied to a stationary object that is in contact with another surface, and kinetic friction occurs when two surfaces rub together.