Tag: friction

All of the above is correct answer. As we know friction is useful but in other means it is also disadvantageous or we can say an evil which is a necessity. Whenever there is movement between two parts of machinery or whenever there is contact between shoes sole and rough road, the parts in contact wear out. Friction causes wear and tear of parts as well as heat is produced which damages the parts.

The statement that friction is not useful, is not true. Friction is advantageous in our daily life. Without friction we will not be able to walk properly, nor drive vehicles etc. 

Frictional force can help a car to slow down and can help to move around the corners without skidding due to the frictional force between tyres and ground . Without friction , brakes of the car will not work and it will be impossible to control the car , due to this we say friction is a necessary evil .

Friction force is the force that opposes the relative motion of an object or the direction opposite to the tendency of relative motion due to the contact of 2 rough surfaces. Hence it is exactly opp to the direction of relative motion of the object.

ADVANTAGES OF FRICTION
Friction plays a vital role in our daily life. Without friction we are handicap.
1. It is becomes difficult to walk on a slippery road due to low friction. When we move on ice, it     becomes difficult to walk due to low friction of ice.
2. We can not fix nail in the wood or wall if there is no friction. It is friction which holds the nail.
3. A horse can not pull a cart unless friction furnishes him a secure Foothold.
DISADVANTAGES OF FRICTION 
Despite the fact that the friction is very important in our daily life, it also has some disadvantages like:
1. The main disadvantage of friction is that it produces heat in various parts of machines. In this way     some useful energy is wasted as heat energy.
2. Due to friction we have to exert more power in machines.
3. It opposes the motion. 
4. Due to friction, noise is also produced in machines.
5. Due to friction, engines of automobiles consume more fuel which is a money loss.
So, Friction is useful for braking moving vehicles; for walking in smooth / slippery surfaces like snow and sand.
Answer (D) friction is harmful

By spitting or sneezing we can get off.

1. Static friction is considered a self adjusting force because it wants the object to remain at rest and not move. Therefore, if an external force is applied, the static force will be equal to the magnitude of external force, until it surpasses the threshold of the motion. Hence friction is a self-adjusting force.
2. If there is no friction between any two surfaces in contact , then we will not be able to walk properly on the earth. Hence friction is necessary, But too much friction will reduce the efficiency of machines. Hence friction is a necessary evil.
3. Friction allows us to hold anything, pick up anything , allows us to go anywhere . Same goes with riding a car or a bike. Thus friction is important force in our daily life.

The friction can be avoided when the contact surface is smooth. But for a rough contact surface, the friction opposes the motion. Thus the given statement is false.

Friction is the force that resists motion when the surface of one object comes into contact with the surface of another. In a machine, friction reduces the mechanical advantage , or the ratio of output to input an automobile, for instance , uses one-quarter of its energy on reducing friction. Hence the efficiency of machine is reduced due to friction.