Tag: increasing and reducing friction

Questions Related to increasing and reducing friction

Can friction ever be eliminated?

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. Yes

  2. No

  3. Sometimes

  4. Depends on the object in regard

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Correct Option: B
Explanation:

However smooth or polished a surface might be, it always has some irregularities. Thus, the friction can never be eliminated.

The substance that helps to ______ friction are called lubricants.

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. increase

  2. decrease

  3. create

  4. eliminate

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Correct Option: B
Explanation:

Oils, grease, graphite, etc., are examples of lubricants. These form a thin layer between the two surfaces in contact thus avoiding them from scrubbing directly against each other. This makes the movement smooth and reduces friction.

Why are the tyres of automobiles grooved?

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. To improve the design

  2. To increase friction

  3. To make it durable

  4. To make it strong

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Correct Option: B
Explanation:

If the tyres of automobiles were smooth, the friction produced would be minimal and thus, it would be difficult to stop or turn the automobile, increasing the risk of accidents. Hence, the tyres are grooved so as to increase the friction between the tyre and the surface of the road.

Kabaddi players rub their hands with soil so that they can :

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. make their skin dry

  2. moisture the hands

  3. get a better grip while holding the opponent

  4. soil the opponent

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Correct Option: C
Explanation:

By rubbing their hands with soil, they make their hands rough. A rough surface has more friction which enhances their grip while holding the opponent.

Which of the following are done to reduce friction?
a) Making grooves in the shoes
b) Polishing rough surfaces
c) Using wheels, ball bearings
d) Creating an air cushion

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. a, b and c

  2. c and d

  3. b, c and d

  4. All of the above

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Correct Option: C
Explanation:
Making grooves in the shoes increases friction.
Polishing rough surfaces makes it smooth, thus reducing friction. 
Wheels and ball bearings create rolling friction which has the least magnitude compared to sliding and static friction.
Air cushion makes a layer of air between two surfaces, which helps in reducing friction.

How do brake pads help in stopping an automobile?

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. Brake pads press on the wheel and increase friction.

  2. Due to braking, the air pressure increases and the wheels stop.

  3. Both A and B

  4. None of the above

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Correct Option: A
Explanation:

The brake pads press on the wheels and increase the friction since the surface of the brake pads and the wheels are irregular, and the rough surface increases friction that opposes the motion of the wheel.

Which of the following are done to increase friction?

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. Greasing the machines

  2. Treading the tyres

  3. Sprinkling powder on the carom board

  4. All of the above

Show answer
Correct Option: B
Explanation:

The tyres are treaded to make it rough so that the frictional force increases when it comes in contact with the road. 

All others are done to decrease friction.

The steps for decreasing friction includes:

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. ball bearing used in moving parts of a machine

  2. the streamlined shape of an aircraft

  3. the layer of air between the hull of a hovecraft

  4. none of these

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Correct Option: A,B,C
Explanation:

1) As rolling friction is less than sliding friction the shafts are fixed on ball bearing so that so that friction is reduced considerably.

2) The friction due to air is reduced by making the automobiles streamlined. Streamline shape allows more air and water to flow easily which offers least resistance.
3) Another way of reducing friction is to separate surfaces by air. This principle is used in hovecraft. The layer of air reduces friction allowing aircraft to move easily.

If we apply oil on door hinges, the friction will:

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. increase

  2. decrease

  3. disappear altogether

  4. will remain unchanged

Show answer
Correct Option: B
Explanation:

Lubrication always decreases friction between two surfaces. Hence putting oil will decrease friction.

In a large commercial complex there are four ways to reach the main road. One of the path has loose soil, the second is laid with polished marble, the third is laid with bricks and the fourth has gravel surface. It is raining heavily and Paheli wishes to reach the main road. The path on which she is least likely to slip is:

physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

  1. loose soil

  2. polished marble

  3. bricks

  4. gravel surface

Show answer
Correct Option: A
Explanation:

Loose soil will provide the maximum friction and hence less chances of slipping.