- #1
kay
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Frictional force opposes relative motion and not just motion. Can you please give an example to further explain this statement? 
Frictional force opposes relative motion?
- Thread starter kay
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In summary, frictional force plays a crucial role in opposing relative motion, not just motion itself. An example of this can be seen in a conveyor belt where the objects on it are initially at rest but are accelerated by the belt's movement. This acceleration is caused by static friction between the belt and the objects, which allows them to move with respect to the ground. In contrast, if there is no interaction between the ground and the object on the belt, there is no friction involved. A car accelerating on level ground is another example, where the force accelerating the car is from the road and is static friction between the road and the tires. This force may oppose relative motion between the tire and the road, but it ultimately accelerates the car
- #2
ehild
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Think of as conveyor belt, initially at rest. There are things on it, also in rest. The belt gets moving, and the things on it will move together with the belt. They must have been accelerated, what was the force?
ehild
ehild
- #3
kay
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so when we consider the friction between the belt and the 'thing', it's static friction?
and when we consider the friction b/w ground and 'thing', it is kinetic friction?
and when we consider the friction b/w ground and 'thing', it is kinetic friction?
- #4
ehild
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If the object does not move with respect to the belt: it is static friction between the belt and the object. It opposes the motion relative to the belt and makes the object move with respect to the ground.
There is no interaction between the ground and the object on the belt (except gravity). Friction is a contact force.
ehild
There is no interaction between the ground and the object on the belt (except gravity). Friction is a contact force.
ehild
Last edited:
- #5
kay
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Thanks a lot! :D 
- #6
Philip Wood
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A car accelerating on level ground is an interesting example. The force accelerating the car (but NOT the energy it acquires) is from the road. The force involved is static friction between the road and the tyres. If the tyres slip on the road the car doesn't accelerate. So although the force opposes relative motion between the bottom of the tyre and the road, by doing so the force accelerates the car! [I've sometimes thought that there were two brilliant discoveries/inventions concerning the wheel. The first was that fitting wheels to a cart, chariot etc. enabled it to be dragged with little resistance, the second was that turning the wheel moved the cart forward.]
Related to Frictional force opposes relative motion?
What is frictional force?
Frictional force is a force that opposes the relative motion between two surfaces in contact.
How is frictional force measured?
Frictional force is typically measured in Newtons (N) using a spring scale or a force sensor.
What causes frictional force?
Frictional force is caused by the microscopic roughness and interlocking of two surfaces in contact with each other.
What factors affect the magnitude of frictional force?
The magnitude of frictional force is affected by the type of material, the roughness of the surfaces, and the amount of force pressing the surfaces together.
How does frictional force impact motion?
Frictional force acts in the opposite direction of motion, so it can either slow down or stop an object's movement or cause it to move in a different direction.
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