Tag: friction: a necessary evil

Questions Related to friction: a necessary evil

You are marooned on a frictionless horizontal surface and cannot exert any horizontal force by pushing against the surface. How can you get off ?

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. by jumping

  2. by spitting or sneezing

  3. by rolling your body on the surface

  4. by running on the plane

Show answer
Correct Option: B
Explanation:

By spitting or sneezing we can get off.

Since there is no friction present we need to spit or sneeze which will produce a suitable friction to get off. Also this will produce a momentum in opposite direction which will help us to move in opposite direcdtion.

Friction is a/an

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. self-adjusting force

  2. necessary evil

  3. important force in daily life

  4. all the above

Show answer
Correct Option: D
Explanation:
  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.

Friction should always be avoid.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

Show answer
Correct Option: B
Explanation:

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.

The efficiency of machine is reduced due to friction.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

Show answer
Correct Option: A
Explanation:

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.

A sphere $S$ roll without slipping, moving with a constant speed on a plank $P.$ The fraction between the upper surface of $P$ and the sphere is sufficient to prevent slipping, while the lower surface of $P$ is smooth and rests on the ground. Initially, $P$ is fixed to the ground by a pin $N.$ If $N$ is suddenly removed:

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. S will begin to slip on P

  2. P will begin to move back wards

  3. the speed of s will decrease, and its angular velocity will increase

  4. there will be no charge in the motion of S and P will still be at rest

Show answer
Correct Option: D

Why do we sprinkle powder before playing carroms?

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. To increase friction

  2. To decrease friction

  3. To increase or decrease the friction depending on the type of the game played

  4. None of these

Show answer
Correct Option: B
Explanation:

It is done just to reduce the friction. On microscopic level, the powder particles offer rolling friction to the striker because of which the striker can be rolled around smoothly.

State whether the statements are true or false:
Oil is used to reduce the friction on door hinges.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Lubrication is another way to make a surface smoother. A lubricant is a slippery substance designed to reduce the friction between surfaces, Since the door hinges are exposed to the atmosphere the chances of corrosion increases and the surface becomes irregular enough to promote friction. Applying oil on the door hinges can reduce the amount of friction and thus it will decrease it.

Friction should always be avoided.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

Show answer
Correct Option: B
Explanation:
The given statement is false.
Friction is a necessary evil because without friction we will not be able to set our bodies in motion or stop the bodies which are in motion. Friction is absolutely necessary in our day to day activities. For eg it is the friction on the ground that helps us to walk and without friction it would not have veen possible to write on a paper.
Hence friction is important and cannot be avoided.

Friction is a force that oppose motion.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

The given statement is true.

Friction always acts in opposite direction to movement i.e it opposes the motion of an object. Air resistance is a frictional force which opposes motion through air.

The efficiency of machine is reduced due to friction.

physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Yes, the statement is true.

Friction introduces losses and decreases efficiency since friction generates heat which is an energy that should be converted in movement. That energy in the form of heat is a loss. Also friction increases increases the wear and tear of a machine thereby decreasing its efficiency.