What is friction Class 11?
Hint: Friction is a type of relative force that acts as a resistance between two bodies that are in contact with each other. In other words when two bodies are in contact with each other there exists a force which opposes their relative motion.
Which is the law of friction answer?
First law of friction: The amount of friction is proportional to the normal force exerted between the surfaces. Second law of friction: Friction does not depend on the area of contact between the object and the surface. Third law of friction: Friction force also depends on the nature of the surfaces in contact.
Who stated the laws of friction?
Guillaume Amontons, after whom the law is named, conducted friction experiments in the 17th century, but the law has long been nicknamed “da Vinci’s law of friction” due to other experiments discovered in his notebooks.
What are various laws of friction?
Laws of dry friction Amontons’ First Law: The force of friction is directly proportional to the applied load. Amontons’ Second Law: The force of friction is independent of the apparent area of contact. Coulomb’s Law of Friction: Kinetic friction is independent of the sliding velocity.
What are 5 types of friction?
They are static friction, sliding friction, rolling friction, and fluid friction. The next sections will explore these forces and when they are applied.
What is principle of friction?
1) The force of friction always acts in a direction, opposite to that in which the body is moving. 2) The magnitude of kinetic friction bears a constant ratio to the normal reaction between the two surfaces. But this ratio is slightly less than that in case of limiting friction.
How is friction calculated?
Friction is a resistive force that prevents two objects from sliding freely against each other. The coefficient of friction (fr) is a number that is the ratio of the resistive force of friction (Fr) divided by the normal or perpendicular force (N) pushing the objects together.
What are the disadvantages of friction?
Three disadvantages of friction are :
- Friction produces heat which damages the moving parts of a machine.
- Friction produces wear and tear on the contacting surfaces. This reduces the life of machine parts, tyres and shoe soles.
- A lot of energy is wasted in overcoming the friction before an object starts moving.
What is friction explain with an example?
Friction acts as a resisting force which is generated , when two solid surfaces slide against one another. Examples :- <> For walking , there is a friction between our shoes / feet . <>There is a friction between the tires of a vehicle and between the road.
What is friction give two example?
Friction is what holds your shoe to the ground. The friction present on the ice is very little, this is the reason why it is hard to walk on the slippery surface of the ice. Writing – A frictional force is created when the tip of the pen comes in contact with the surface of the paper.
What are some examples of useful friction?
Helpful frictional forces friction between our shoes and the floor stop us from slipping. friction between tyres and the road stop cars from skidding. friction between the brakes and wheel help bikes and cars to slow down.
Where is friction not useful?
Friction is sometimes unhelpful. For example, if you don’t lubricate your bike regularly with oil, the friction in the chain and axles increases. Your bike will be noisy and difficult to pedal. When there is a lot of friction between moving parts, energy is lost to the surroundings as heat.
What are some examples of harmful friction?
HARMFUL FRICTION
- Slipping on ice.
- Wet roads.
- Mudslides.
Which is wasteful friction?
Answer: Though friction is said to be a waste of energy in most of the times, it is really useful at many times in regular life. We need to increase the frictional force while pressing the brakes of a car or a bicycle to stop it at the right time.
Which is wasteful friction example?
In any type of vehicle—such as a car, boat or airplane—excess friction means that extra fuel must be used to power the vehicle. In other words, fuel or energy is being wasted because of the friction. Fluid friction or air resistance can greatly reduce the gas mileage in an automobile.
What direction is the force of friction?
The frictional force is the other component; it is in a direction parallel to the plane of the interface between objects. Friction always acts to oppose any relative motion between surfaces.
What is the coefficient of friction called?
Coefficient of friction, ratio of the frictional force resisting the motion of two surfaces in contact to the normal force pressing the two surfaces together. It is usually symbolized by the Greek letter mu (μ). Mathematically, μ = F/N, where F is the frictional force and N is the normal force.
What are the 2 types of friction?
There are two main types of friction, static friction and kinetic friction. Static friction operates between two surfaces that aren’t moving relative to each other, while kinetic friction acts between objects in motion.
What is a high coefficient of friction?
A coefficient of friction that is more than one just means that the frictional force is stronger than the normal force. An object such as silicone rubber, for example, can have a coefficient of friction much greater than one.
What is the lowest coefficient of friction?
PTFE has the lowest recorded m value for any material with a dynamic coefficient of friction of between 0.05 and 0.15 and a static coefficient of friction of approximately 0.05. The other fluorocarbons i.e. FEP , PFA, ETFE and ECTFE all have extremely low coefficients of friction in the region of 0.14 to 0.25.