Wed. Jul 6th, 2022

1 Mark Questions for NCERT Solutions for Class 8 Science Chapter 12

Question 1.
Define friction.
Answer:
Friction is the force which resists the motion of a body, while moving on a surface.

Question 2.
What is meant by sliding friction ?
Answer:
When one surface is sliding over the other, sliding friction comes into play.

Question 3.
When does static friction come into play ?
Answer:
Static friction comes into play to counter balance the applied force on the body.

Question 4.
What are lubricants ?
Answer:
The substances which reduce friction are called lubricants.

Question 5.
What is rolling friction ?
Answer:
When one body rolls over the surface of another body, the resistance to its motion is called the rolling friction.

Question 6.
What are fluids ?
Answer:
Fluids is the common name given to gases and liquids.

Question 7.
Do fluids exert friction ?
Answer:
Yes, fluids also exert friction.

Question 8.
What is meant by air resistance ?
Answer:
There is friction between a moving object and the air through which it moves, known as air resistance.

Question 9.
What is meant by drag ?
Answer:
The frictional force exerted by fluids is known as drag.

Question 10.
Is friction a contact force or non-contact force ?
Answer:
Contact force.

Question 11.
Why is it difficult to walk on ice ?
Answer:
It is difficult to walk on ice because the friction between feet and ice is less,

Question 12.
When a boat is moving in the river, does the water offer force of friction to its movement ?
Answer:
Yes, the water opposes the movement of the boat.

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