NCERT Class VIII Science Solutions: Chapter 11-Force and Pressure Part 2

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Question 5:

In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.

  1. Squeezing a piece of lemon between the fingers to extract its juice.

  2. Taking out paste from a toothpaste tube.

  3. A load suspended from a spring while its other end is on a hook fixed to a wall.

  4. An athlete making a high jump to clear the bar at a certain height.

Answer:

Effect of the Force
Effect of the force

S. No.

Agent

Object

Effect

1.

Fingers

Lemon

Juice is extracted by force.

2.

Fingers

Toothpaste tube

Toothpaste coming out by force.

3.

Load

Spring

Expansion of spring.

4.

Athlete

Athlete’s body

Athlete jump over the bar.

Question 6:

A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron?

Answer:

The force due to hammering change the shape of the piece of iron.

The force due to hammering change the shape of the piece of …

Hammering Change the Shape

Question 7:

An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?

Answer:

The force which is responsible for the attraction between the ball and the wall is electrostatic force.

When we rub the balloon by a synthetic cloth, it gets charged. When it is taken near the wall, it will get attracted towards the uncharged wall because of the electrostatic force which is the force exerted by a charged body on another uncharged body.

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