# Centripetal Force: Why Does Friction Provide It?

• siddharth5129
The steering mechanism of the vehicle continuously provides this centripital force to keep the vehicle in a circular path. That is the source of the centripital force that causes the vehicle to move in a circular path.In summary, the requisite centripetal force for the circular motion of a vehicle is provided by friction, which opposes the centrifugal outward force. The point of application of this force is at rest and does not cause any work to be done. This force is continuously provided by the steering mechanism of the vehicle to keep it in a circular path.

#### siddharth5129

My textbook says that the requisite centripetal force for the circular motion of a vehicle is provided by friction. I don't get that .... i mean , shouldn't friction oppose relative motion ...so , seeing as the direction of motion of the car is along the tangent to the curve , shouldn't friction act along the tangent to the curve in the opposite direction...what gives?

If there's no friction, the vehicle cannever make that turn. Or if the frictional force is LESS than the needed centripetal force, the vehicle will slide. Guess which direction it will slide?

In any case, this is all hand-waving. All you need to do is draw a free-body diagram and account for all the forces involved. If you follow what you had in mind, you'll see something missing, i.e. where is the source of the centripetal force that causes the vehicle to move in a circular path?

Zz.

In an instantaneous sense you can consider the car to be moving tangentially to the curve, but that is exactly the type of thinking that got you stuck.

Consider what the car does through the entire turn. What does the car have to do to turn (not meaning "turn the wheels," but rather is there a force need be applied)?

Edit- wow, beaten to a response at 4 AM...

siddharth5129 said:
My textbook says that the requisite centripetal force for the circular motion of a vehicle is provided by friction. I don't get that .... i mean , shouldn't friction oppose relative motion ...so , seeing as the direction of motion of the car is along the tangent to the curve , shouldn't friction act along the tangent to the curve in the opposite direction...what gives?
Careful. Just because the car is moving to the right (say) doesn't mean friction acts to the left, since the tires are rolling. It's not the same as if you were to drag a block of wood to the right--in which case friction would act to the left.

Friction opposes slipping between surfaces. The contact surfaces are the tire and the ground. Realize that the tire (presumably) is rolling without slipping--thus the friction involved is static friction. As ZapperZ says, you must analyze the forces acting on the car and its acceleration to understand the direction of the friction force.

shouldn't friction oppose relative motion

well in a sense, i think it is opposing relative motion,
for that u hav to analyse the point where friction is acting..
if u can see it, car bending on a right turn actually have a tendency of keeping to the left due to inertia,
friction opposes this.

also, there is a difference between rolling, static and kinetic friction...
while turning, static friction is acting as the point of application of force is always at rest
i.e it does not RUB or SLIP on the ground.
kinetic friction acts when slipping occurs.
Rolling friction , is suppose is irrelevant as we can assume road is hard

Caesar_Rahil said:
well in a sense, i think it is opposing relative motion,
for that u hav to analyse the point where friction is acting..
if u can see it, car bending on a right turn actually have a tendency of keeping to the left due to inertia,
friction opposes this.

also, there is a difference between rolling, static and kinetic friction...
while turning, static friction is acting as the point of application of force is always at rest
i.e it does not RUB or SLIP on the ground.
kinetic friction acts when slipping occurs.
Rolling friction , is suppose is irrelevant as we can assume road is hard

I can see your point about the car having a tendency of keeping to the left due to inertia ...but i don't get why the point of application of force is always at rest ... , isn't it moving along with the car ...so why does static friction act?

The frictional (centripital) force opposes the centrifugal outward force. Neither of these is in the instantaneous direction of motion dx, so their vector product with dx is zero, and so no work (F*dx) is done and the vehicle velocity ideally does not change.

## 1. What is centripetal force?

Centripetal force is the force that keeps an object moving in a circular path. It is directed towards the center of the circle and is necessary for an object to constantly change direction without moving in a straight line.

## 2. How is friction related to centripetal force?

Friction is one of the forces that can provide centripetal force. When an object is moving in a circular path, there is a force acting in the opposite direction of the motion, known as the centrifugal force. Friction acts in the opposite direction of the centrifugal force and towards the center of the circle, providing the necessary centripetal force.

## 3. Can other forces provide centripetal force?

Yes, besides friction, other forces can also provide centripetal force. These include tension, gravity, and electromagnetic forces. The specific force that provides centripetal force depends on the situation and the objects involved.

## 4. What factors affect the amount of centripetal force provided by friction?

The amount of centripetal force provided by friction depends on the coefficient of friction, the mass of the object, and the speed of the object. A higher coefficient of friction, a higher mass, or a higher speed will result in a higher centripetal force provided by friction.

## 5. Can centripetal force be greater than friction?

Yes, it is possible for the centripetal force to be greater than friction. In this case, the object will continue to move in a circular path, but the friction force will not be enough to keep it on the path. This can result in the object slipping or sliding out of the circular path.