NCERT Solutions for Class 8 Science Chapter 11 - Force And Pressure

Here are the important topics from Chapter 11 of Class 8 Science - Force and Pressure. You should focus more on these topics to excel in the examination.

1. Force – A Push or a Pull

2. Forces are due to an Interaction

3. Exploring Forces

4. A Force can Change the State of Motion

5. Force can Change the Shape of an Object

6. Contact Forces

7. Non-Contact Forces

8. Pressure

9. Pressure Exerted by Liquids and Gases

10. Atmospheric Pressure

Now, let us solve the NCERT exercises based on the topics given above. These topics are briefly discussed later in this article. 

NCERT Class 8 Exercise and Solutions of Chapter 11 Force and Pressure 

1. Give two examples of each of the situations in which you push or pull to change the state of motion of objects.

Ans: The following are the required examples-

Push force examples: 

1. A toy car is at rest and is moved by applying a push force.

2. We move a bicycle by pushing it.

Pull force examples include:

1. Taking out a drawer.

2. Drawing water from a well by pulling a rope.

2. Give two examples of situations in which applied force causes a change in the shape of an object.

Ans: The following are two instances of situations in which a force can modify the shape of an object:

1. When plastic bottles are squeezed, they change shape.

2. A rubber band's shape changes when it is stretched.

3. Fill in the blanks in the following statements. 

(a) To draw water from a well we have to ____ at the rope. 

(b) A charged body ____ an uncharged body towards it. 

(c) To move a loaded trolley, we have to ______ it. 

(d) The north pole of a magnet _____ the north pole of another magnet.

Ans:

1. To draw water from a well we have to pull at the rope. 

2. A charged body attracts an uncharged body towards it. 

3. To move a loaded trolley, we have to either push or pull it. 

4. The north pole of a magnet repels the north pole of another magnet.

4. An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms. 

muscular, contact, noncontact, gravity, friction, shape, attraction 

1. To stretch the bow, the archer applies a force that causes a change in its _______. 

2. The force applied by the archer to stretch the bow is an example of ________ force.

3.  The type of force responsible for a change in the state of motion of the arrow is an example of a _______ force. 

4.  While the arrow moves towards its target, the forces acting on it are due to _____ and that due to _____ of air.

Ans: 

1. To stretch the bow, the archer applies a force that causes a change in its shape. 

2. The force applied by the archer to stretch the bow is an example of muscular force. 

3. The type of force responsible for a change in the state of motion of the arrow is an example of a contact force.

4. While the arrow moves towards its target, the forces acting on it are due to gravity and that due to friction of air.

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. 

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

(b) Taking out paste from a toothpaste tube. 

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

(d) An athlete making a high jump to clear the bar at a certain height.

Ans: 

1. When squeezing a lemon, the hands exert muscular force on the fruit. As a result, the lemon's form shifts.

2. The hand exerts muscular strain on the tubing of the syringe. As a result of the toothpaste, the tube's shape changes.

3. A downward force is applied to the spring by the suspended weight. The spring lengthens as a result of this.

4. When attempting a high leap, an athlete's feet exert muscular power on the ground. As a result, he leaps over the bar, changing his state of motion.

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? 

Ans: A blacksmith hammers a molten iron piece. He imparts a massive compressive force to the iron, causing it to alter shape.

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?

Ans: An inflated balloon becomes charged when it is rubbed against a wall after being rubbed with synthetic fabric. The balloon attaches to the wall because a charged body attracts an uncharged body. The electrostatic force is the force that exists between the charged balloon and the wall.

8. Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the forces acting on the bucket do not bring a change in its state of motion.

Ans: The muscular force applied by the hand and the weight owing to gravity are the forces operating on the plastic bucket. Because these two forces are equal and opposite one another, there is no change in the state of motion.

9. A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.

Ans: The force of gravity/weight and friction caused by the earth's atmosphere are the two forces that act on the rocket shortly after launch.

10. When we press the bulb of a dropper with its nozzle kept in water, the air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to: 

(a) pressure of water

(b) the gravity of the earth

(c) the shape of a rubber bulb 

(d) Atmospheric pressure

Ans: (d) Atmospheric pressure. When air escapes from the dropper's nozzle, it creates a pressure difference, which causes water to be pulled into the nozzle.

Important Definitions of CBSE Class 8 Chapter 11 Force and Pressure 

What is Force?

In Science, when an object is displaced or tends to displace from its original position, it requires an external agent which is called force. It is of two types: push force and pull force. Force is a vector quantity as it has both magnitude and direction. 

What Can a Force Do?

• It can change the state of the motion.

• It can change the direction of an object.

• It can change the shape of an object. 

What is Friction?

Friction is the force which is actually responsible for changing any kind of state of motion. For example, when an object slide from a smooth surface then the friction is less compared to the object sliding from a rough surface. 

What is Pressure?

Pressure on an object is defined as the force acting on its square unit surface. 

Pressure = Force/Area of surface

Its unit is newton/m2. The pressure of the air around us is known as atmospheric pressure. 

Do Liquid and Gases Exert Pressure on Surface?

Yes, both liquid and gases exert pressure on the surface. It can be understood with an example. If we filled a balloon with water or air, then after a certain amount of time it will burst. It is because of the pressure exerted by air or water on the surface of the balloon.  

Important Points of Chapter 11 Science Class 8

• By squeezing the lemon, we create a muscular force that extracts the juice. As a result, the lemon's form is altered.

• We use our muscles to get the paste out of the toothpaste tube. The toothpaste tube changes shape as a result of the muscle force pressing on it.

• The spring is pushed downwards by the force exerted by the suspended load. The spring is stretched as a result. As a result, its shape is altered.

• The muscular force exerted by the athlete's feet on the ground pushes the ground. As a result, he is able to jump over the bar. As a result, he changes his condition of motion.

NCERT Solutions for Class 8 Science - Free PDF Download

Vedantu’s NCERT solutions will give you clarity regarding various aspects of this chapter, which will consequently help you to solve questions from this chapter easily. In Chapter 11 Force and Pressure, you will come across the questions on applied force, changes in the object shape, etc. Some questions like the difference between force and pressure appear often in the exams which are explained in detail in the given solution.

The other essential types of questions are based on objects and force. Practicing these kinds of questions in this chapter will ensure that you have a good understanding of the topic. NCERT Class 8 Science Solutions for Force and Pressure PDF is also available here and can be accessed both offline and free of charge by students. Download the PDF Solution now for free.

Benefits of NCERT Solutions for Class 8 Science

Our proficient and experienced teachers have formulated all the solutions in a well-structured format to make your learning process easier. The following are the benefits you would get if you avail of our free Class 8 Science Chapter 11 Solutions.

• All the available solutions are accurate and of high quality.

• All the solutions are as per the CBSE guidelines. 

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• PDF Solutions are available online for free and can be downloaded for offline use as well.

• Detailed and precise solutions for all the problems. 

• Especially prepared by proficient and experienced subject experts.

By downloading the free PDFs from Vedantu, you would obtain clarity regarding issues that you’re facing with Class 8 Science questions.

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Not only for Science, but Vedantu’s study material is also available for every subject for every class. Each topic has been taken care of by our subject experts. All the solutions are well-crafted for students and all solutions fit the CBSE guidelines. Each topic in every subject has been explained in an organized manner and all the study materials and test-papers have been formulated accordingly. It will help students to find the solution to any particular problem quite easily. We have also added several miscellaneous questions that would help you understand the topic clearly.

Chapter wise NCERT Solutions for Class 8 Science

• Chapter 1 - Crop Production and Management

• Chapter 2 - Microorganisms: Friend and Foe

• Chapter 3 - Synthetic Fibres and Plastics

• Chapter 4 - Materials: Metals and Non-Metals

• Chapter 5 - Coal and Petroleum

• Chapter 6 - Combustion and Flame

• Chapter 7 - Conservation of Plants and Animals

• Chapter 8 - Cell - Structure and Functions

• Chapter 9 - Reproduction in Animals

• Chapter 10 - Reaching The Age of Adolescence

• Chapter 12 - Friction

• Chapter 13 - Sound

• Chapter 14 - Chemical Effects of Electric Current

• Chapter 15 - Some Natural Phenomena

• Chapter 16 - Light

• Chapter 17 - Stars and The Solar System

• Chapter 18 - Pollution of Air and Water

Along with this, students can also view additional study materials provided by Vedantu, for Class 8:

• NCERT Exemplar for class 8 Science Chapter 11

• CBSE Revision Notes for class 8 Science Chapter 11

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