Tag: friction: a necessary evil

Questions Related to friction: a necessary evil

Why do we sprinkle powder before playing caroms?

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

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Correct Option: B
Explanation:

Powder acts as a lubricant to the surface and reduces friction so that the game can be carried on smooth surface.

Powder is a lubricant

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. None

  4. Can't say

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Correct Option: A
Explanation:

Powder is a lubricant because it reduces the friction and makes the surface smooth.

To keep machines running smoothly and to avoid wear and tear of machines, the best and the most commonly used lubricant is:

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

  1. Powder

  2. Sand

  3. Oil

  4. Water

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Correct Option: C
Explanation:

Oil is the best and the most commonly used lubricant used for keeping machines running smoothly and to avoiding wear and tear of machines as it reduces the friction more effectively.

A car will skid more on a wet road than on a dry one because, between the dry road and the car tyres there is more:

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

  1. Friction

  2. Lubricant

  3. Gravity

  4. Heat

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Correct Option: A
Explanation:

A vehicle skids on the road due to less friction between the road and the vehicle tyres.

Any substance which is used to reduce the roughness of a surface is called a:

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

  1. Lubricant

  2. Lubrant

  3. Lubrication

  4. None of these

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Correct Option: A
Explanation:

Lubricants reduce the rounghness of an surface and make them smooth. Smooth surfaces have less friction due to reduced roughness.

Friction can be increased by increasing:

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

  1. Smoothness of the surface

  2. Grease on the surface

  3. Roughness of the surface

  4. Lubricating the surface

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Correct Option: C
Explanation:

Rough surface is uneven so it provides more resisitance to motion of a body hence the frictional force increases.

The force which prevents us from slipping while walking on the road is:

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

  1. muscular force of our body

  2. gravitational pull by earth

  3. frictional force

  4. balanced forces of nature

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Correct Option: C
Explanation:

When we push the ground with our feet, the friction provides a forward reaction to our push and sends us forward. Walking on smooth ground is difficult because the frictional force is not great enough to prevent slipping.


Option C is correct.

In which of the following cases more friction is desirable?

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

  1. Movement of piston in a cylinder

  2. Braking of a vehicle

  3. Running on a track

  4. All of the above

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Correct Option: B
Explanation:

Answer is B.

Brakes is a type of automotive brake that slows or stops a vehicle by converting kinetic energy into heat energy, via friction. The heat energy is then dissipated into the atmosphere. 
Hence, braking of a vehicle happens due to friction.

Spikes are provided in the shoes of athlete

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

  1. For decoration

  2. To increase friction

  3. To decrease friction

  4. None of the above

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Correct Option: B
Explanation:

Answer is B.

Spikes are provided on the soles of shoes of athletes to increase the friction between the shoe and the ground.

The surface of the head of a matchstick and sides of a match box are deliberately made rough to

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

  1. Increase friction

  2. Decrease friction

  3. Increase pressure

  4. Decrease amount of heat

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Correct Option: A
Explanation:

Answer is A.

A match is a small stick of wood or strip of cardboard with a solidified mixture of flammable chemicals deposited on one end. When that end is struck on a rough surface, the friction generates enough heat to ignite the chemicals and produce a small flame. Some matches, called strike-anywhere matches, may be ignited by striking them on any rough surface.
Hence, the surface of the head of a matchstick and sides of a match box are deliberately made rough to increase friction.