NCERT Class VIII Science Solutions: Chapter 12-Friction Part 2

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Question 7:

A boy rolls a rubber ball on a wooden surface. The ball travels a short distance before coming to rest. To make the same ball travel longer distance before coming to rest, he may

  1. Spread a carpet on the wooden surface.

  2. Cover the ball with a piece of cloth.

  3. Sprinkle talcum powder on the wooden surface.

  4. Sprinkle sand on the wooden surface.

Answer: C

Question 8:

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

  1. Loose soil.

  2. Polished marble.

  3. Bricks.

  4. Gravel.

Answer: D

VERY SHORT ANSWER QUESTIONS

Question 9:

Two blocks of iron of different masses are kept on a cemented floor as shown in Fig. Which one of them would require a larger force to move it from the rest position?

As showing in fig is a Two blocks of iron

Two Blocks of Iron

As showing in fig is a Two blocks of iron

Answer:

Larger force will be required to move the heavier block.

Question 10:

Will force of friction come into play when a rain drop rolls down a glass window pane?

Answer:

Yes

Image of Force of friction

Image of Force of Friction

Image of Force of friction

Question 11:

Two boys are riding their bicycles on the same concrete road. One has new tyres on his bicycle while the other has tyres that are old and used. Which of them is more likely to skid while moving through a patch of the road which has lubricating oil spilled over it?

Answer:

The bicycle with worn out tyres is more likely to skid.

Question 12:

Fig shows two boys applying force on a box. If the magnitude of the force applied by each is equal, will the box experience any force of friction?

As showing in fig is a two boys applying force on a box

Two Boys Applying Force on a Box

As showing in fig is a two boys applying force on a box

Answer:

Force of friction will be zero as the net force on the box is zero