Class 8 Science Friction Chapter 12 Set 3

Question 1

Which lubricant is generally used on motorcycle machines to increase the efficiency of the vehicles?

Accepted Answer

Grease

Answer

Talcum powder

Answer

Varnish

Answer

Acid

Question 2

Why is it more difficult to walk on a Sunday road than on a concrete road?

Accepted Answer

Because the friction between sand and feet is less than that between concrete and feet

Answer

Because Sand is soft and Concrete is hard

Answer

Because sand is grainy but Concrete is smooth

Answer

Decrease the friction between sand and feet is more than that between concrete and feet

Question 3

Friction between two flat surfaces can be reduced by

Accepted Answer

Greasing

Answer

Hammering

Answer

increase the thickness of the surface

Answer

Decreasing the area of the contact

Question 4

It is difficult to drive a vehicle whose tire is not properly inflated because

Accepted Answer

Sliding friction comes into play

Answer

Deformation increases rolling of friction

Answer

Deformation decreases sliding friction

Answer

friction is reduced to Zero

Question 5

What kind of friction is experienced by a dolphin swimming through the ocean?

Accepted Answer

Fluid friction

Answer

Static friction

Answer

Sliding friction

Answer

Rolling friction

Question 6

A boy sits halfway down a grassy slope, what forces stop him from sliding down?

Accepted Answer

Friction

Answer

weight

Answer

Gravity

Answer

All of the above

Question 7

Why is sand spread on tracks covered with snow?

Accepted Answer

To increase the force of friction

Answer

To decrease the force of friction

Answer

To melt the Ice

Answer

Because sand is had

Question 8

Which of the following is not an advantage of friction?

Accepted Answer

it enables rubber pads to be rubbed off

Answer

It enables vehicles to move on the ground

Answer

it enables drawing to be made on paper

Answer

it enables fallen things to be picked up

Question 9

If the surface is smoothened, how will it affect friction?

Accepted Answer

friction will decrease

Answer

friction will increase

Answer

friction will remain same

Answer

can not be computed

Question 10

The sole of the shoes becomes plain after wearing it for several months. The reason is-

Accepted Answer

wearing out due to friction

Answer

wearing out due to no friction

Answer

sale is of bad quality

Answer

none of the above

CHAPTER-12 FRICTION (SET-3)

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