Tag: friction: a necessary evil

Questions Related to friction: a necessary evil

Friction reduces efficiency of machines due to:

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

  1. Production of heat

  2. Wearing out of moving parts

  3. Increase in energy consumption

  4. AlI of the above

Show answer
Correct Option: D
Explanation:

Answer is D.

Efficiency is relate to energy conversion performance. A system that can convert energy entirely and completely into energy of another form performs the conversion at 100% efficiency. 
The heat produced by friction cannot be used to recover 100% of the mechanical energy that was converted into heat, the effect of friction is to reduce the (energy conversion) efficiency of machines. 
The parts of the machine wear and tear due to contimuous usage.
More the friction more the enrgy consumption.
Hence, all the options are correct.

_______ is responsible for wear and tear of machine parts.

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

  1. Oil

  2. Steel

  3. Friction

  4. Smoothness

Show answer
Correct Option: C
Explanation:

Friction is responsible for wear and tear of machine parts.
Friction is the main force that is responsible for the wear and tear of machinery, this is why mechanical parts are sometimes oiled, to minimize the friction present.

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:

We will need friction to roll or run on any surface. In our case, we have a frictionless surface. Hence, by conservation of linear momentum sneezing can make us move on that surface.

heat is produced whenever work is done against 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

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Correct Option: A
Explanation:

When friction is present, there is a loss of energy. Since frictional force have done work and the energy is lost. Due to this frictional force is released in the form of heat energy.

_______ helps in writing with a pen or pencil on a paper.

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

  1. Magnetic force

  2. Electric charge

  3. Chemical force

  4. Frictional force

Show answer
Correct Option: D
Explanation:

The irregularities between the paper and the pen or pencil create friction. Due to friction, the particles of ink or lead stick to the paper and get locked in its irregularities. If there would be no friction between the paper and pen or pencil, the ink/lead would not stick to the paper and we would not be able to write.

Which of the following is true for friction?

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

  1. It is necessary to perform many tasks.

  2. It produces heat.

  3. It wears out the surfaces in contact.

  4. All of the above

Show answer
Correct Option: D
Explanation:

Friction is important to perform many tasks. It also produces heat in the process and since the two surfaces keep rubbing against each other, they gradually wear out.

State whether the given statement is true or false :

Friction is necessary to perform many tasks. 

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:

Friction helps to lock the two surfaces in contact. 

However, if there was no friction, we would not be able to perform even simple tasks like writing on a paper, or fixing a nail in the wall, stopping or turning an automobile, or even something as simple as tying a lace knot. However, in some cases it is desirable to reduce friction but it can never be eliminated.

Friction is _____ in some situations.

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

  1. desirable

  2. undesirable

  3. both A and B

  4. none of the above

Show answer
Correct Option: C
Explanation:

Friction is both desirable and undesirable depending on the situation. For example, the tyres of an automobile are grooved to increase friction. However, the ball bearings in the same automobile are regularly oiled to reduce friction and ensure smooth functioning of the engine.

In what ways is friction harmful?

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

  1. It causes wear and tear to the surfaces.

  2. Much energy is lost in overcoming friction.

  3. Both A and B

  4. None of these

Show answer
Correct Option: C
Explanation:

Friction comes into play when two irregular surfaces come in contact. The continuous rubbing of these surfaces together causes it to gradually wear out. Also, much of the applied force or energy is wasted in overcoming the force of friction. Hence, it is considered as evil, but it is necessary too.

The friction between two bodies produces

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

  1. Motion

  2. Expansion

  3. Heat

  4. None

Show answer
Correct Option: C
Explanation:

The friction is a force which occurs between two bodies, when say one of them is at motion/ or at both of them in a motion. The rubbing of hand is an example of friction which causes warm feeling in hands.