Anonymous
Anonymous asked in Science & MathematicsPhysics · 10 years ago

# Which direction does the friction force act on bicycle tires? Both front and rear.?

The bike's tires are both moving in the anticlockwise direction.

Relevance
• 10 years ago

In bicycle, pedalling is done on rear wheel. This means that we try to rotate the rear wheel to move forward. The rear wheel pushes the ground backwards and gets the forward frictional force which pushes the bicycle forward.

The front wheel is being pushed forward (through the connecting rod between the rear and front wheels) which results in the backward frictional force on its tire which rotate it in the same direction as the rear wheel.

The static frictional force which acts on both the wheels is a friendly force that helps the bicycle move without loss of energy. Energy loss is due to rolling friction which is backwards on both the wheels.

Conclusion:

Backward static frictional force (opposite to the direction of motion) on the front wheel and forward static frictional force (in the direction of motion) on the rear wheel. Rolling frictional force is backwards on both the wheels. There will be no kinetic friction on the bicycle unless it skids due to sudden application of brakes or due to muddy and slippery road.

As the bicycle tires are moving in the anticlockwise direction, bicycle is moving from right to left. In this case,

( i )

Static frictional force acts on the front wheel from left to right (opposite to the motion of the bicycle) and on the rear wheel from right to left (in the direction of motion of the bicycle). This is a friendly force which helps bicycle move forward and no work is done against it.

(ii)

Rolling friction acts on both the wheels from left to right (opposite to the motion of the bicycle) and work is done to overcome it.

(iii)

Kinetic friction is absent as long as the bicycle does not skid. It is from left to right (opposite to the motion of the bicycle) in the case of skidding. If kinetic frictions acts, work will have to be done against it which will result in loss of kinetic energy and hence speed of the bicycle.

(iv)

There is also the frictional force in the bearings of the wheels which will need more force to accelerate the bicycle and more energy to maintain the speed if the bearings are not sufficiently lubricated.

• 3 years ago

Rolling Friction And Bicycle Tires

• 10 years ago

it is very true that friction acts against the direction of motion actually there is an extension to this statement that needs to be considered which is more relevant and that is friction acts against the direction of motion or the tendency for motion. the wheel comes into contact with respect to the ground and travels along with it without slip and leaves contact. this means that the case of friction is a case of static friction and not sliding or dynamic friction. thus the friction force is not moving through any distance and consequently does no work. on the other hand this friction is what we call the traction capability because if we apply a greater force at the point of contact than can be supported by this friction force (traction force) the wheel would skid.

thus the friction force would be directed in the direction of motion of the bicycle on both the wheels in other words from right to left

• 10 years ago

Frictional force acting upon any object acts opposite to the direction of the body, in this case the bicycle tires.

considering a bicycle moving forward and you are looking at it from the side( so that you see a circle view of the tire), the tires would be rotating clockwise( unlike your question), and the part of the tire touching the ground is moving left( clockwise from 60'clock position to 12o'clock position) which causes the frictional for to act right, and the force acting is rolling friction. But when you apply break, the tire will stop rotating and the surface touching the ground and tire as a whole will be trying to move right or forward due to momentum causing sliding friction to act to the left side.

Any further questions or clarification needed, hope it helped, god bless you.

• 10 years ago

Let us imagine there is no friction at all between the tire and road.

The cycle does not move forward, since there is no forward pulling force. However, the back wheel rotates in the anticlockwise direction (as stated in the problem)

And the front wheel will have no rotation, as there is no torque to rotate the front wheel

If there is friction between the back tire and wheel and there is no friction between the front tire and road, the frictional force acts and pushes the cycle forward to the left.

Thus the frictional force acts toward left on the back wheel. However the front wheel slides on the road without any rotation (since there is no friction between the front tire and road.

Now let there be friction in the front tire and road also. Since the cycle moves to the left, the sliding friction acts in the opposite direction of the motion of the cycle and hence it acts toward right causing the wheel to rotate in the anticlockwise direction. Once rotation started, there is rotation with out slipping.

Thus in the back wheel the friction acts toward left and in front wheel it acts toward right and the front wheel rotates with out slipping.

To reduce the forward velocity of the cycle, the friction in the back wheel acts toward right and in the front wheel it acts toward left causing the anticlockwise rotation of the front wheel to slow down.

In both wheels there is rolling friction which is so small and can be ignored at present and can be dealt with if needed.

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• 4 years ago

Yes. The rear wheel is being pedalled such that the applied force is directed backwards so the friction acts forwards. The front wheel isn't pedalled. The motion of the bike pushes on it and the ground resists and turns the wheel in the direction of the friction, i.e. aiming backwards.

• 10 years ago

Friction force act on bicycle tires in opposite direction

• 10 years ago

If the tires are moving anticlockwise, then the bike is moving left across your field of vision. But the bottom of the bike tire is moving left to right, so friction is moving right to left.

• Anonymous
10 years ago

Friction force acts in the opposite direction of travel.

• Steve
Lv 7
10 years ago

Right