Important Questions for CBSE Class 8 Science Solutions Chapter 11 - Force and Pressure

Multiple Choice Questions

1. Which one of the following forces always opposes motion?

1. gravitational force

2. electrostatic force

3. muscular force

4. friction

Ans: D. friction

2. Pressure is defined as _____________.

1. force per unit area

2. force per square unit area

3. force

4. force per area

Ans: A. force per unit area

3. Which one of the following statements is false about force.

1. Forces applied to an object need not to be in the same direction.

2. No objects interaction is required for a force to come into play.

3. Motion imparted to objects will be due to the action of a force.

4. The strength of a force is usually expressed by its magnitude.

Ans: B. No objects interaction is required for a force to come into play.

4. When a force applied on an object are equal and opposite, then this force

1. May move the object.

2. Change the shape of the object and may move the object.

3. May stop a moving object.

4. Do not move the object but may cause a change in its shape.

Ans: D. Do not move the object but may cause a change in its shape.

5. Leaves and fruits fall to the ground when they get detached from a plant. Which one of the following forces is acting on it?

1. muscular force

2. magnetic force

3. gravitational force

4. electrostatic force

Ans: C. gravitational force

6. Which one of the following is an example of contact force?

1. magnetic force

2. muscular force

3. electrostatic force

4. gravitational force

Ans: B. muscular force

Very Short Answer Questions                                                           1 Marks

1. What is a force?

Ans: Force is a push or a pull exerted on one object from another.

2. The strength of a force is usually expressed by its_______________.

Ans: Magnitude.

3. Objects or things fall towards the earth because it pulls them. This force is called the ______.

Ans: Force of gravity or gravitational force.

4. Write the formula to find out pressure.

Ans: The formula of pressure is:

Pressure= Force/Area

P=F/A

5. State whether the following statement is True or False.

Gases exert pressure on the walls of their container.

Ans: True. Gaseous particles move randomly and due to this motion, they also hit the walls of the container, thus creating pressure on its walls.

6. The pressure exerted by this air is known as __________________.

Ans: Atmospheric pressure.

7. Which force acts on every object in the universe?

Ans: Gravitational force acts on every object in the universe.

Short Answers Questions                                                                   2 Marks

1. Find out the type of force acting on the below situations.

1. A coin or a pen falls to the ground when it slips out of your hand.

Ans: Gravitational force acts when something falls to the ground after slipping out of our hand.

2. A boat comes to rest if we stop rowing it.

Ans: A boat comes to rest if we stop rowing due to friction.

3. When a person lifts a bucket of water.

Ans: Muscular force acts when a person lifts a bucket of water.

2. Describe the state of motion of an object.

Ans: The motion of an object is defined by its speed and direction. The resting state is considered to be the state of zero speed. An object may rest or move; these can be its two states of motion.

3. Write one point of difference between contact and non-contact force with an example.

Ans: A point of difference between contact and non-contact force along with an example is provided below,

4. Why do you think a ball rolling along the ground gradually slows down and comes to rest?

Ans: A ball rolling along the ground gradually slows down and comes to rest due to friction. This force of friction acts between the surface of the ball and the ground and acts opposite to the direction of motion which brings the ball to rest after some time.

5. Porters place a round piece of cloth on their heads when they have to carry heavy loads. Why?

Ans: Porters place a round piece of cloth on their head when they have to carry heavy loads because this increases the area of contact of the load and their head which decreases the pressure on their head. Since pressure is inversely proportional to the area of contact. This makes it easier for porters to carry heavy loads.

6. What type of force is friction – contact or non-contact? Why?

Ans: Friction is a contact force because it arises due to contact between two surfaces. The surface of contact witnesses’ frictional motion while rubbing against each other. This force acts in the direction opposite to the direction of motion.

7. Why do you think pressure acts on the area of a surface?

Ans: Pressure is inversely proportional to the area of the surface, that is, a small area will provide greater pressure with the same amount of force applied. This means that a pointed needle will hurt more or exert more pressure than a plank of wood with the same force applied on both.

8. Do you think sometimes the application of force does not result in a change in the state of motion? Describe with an example.

Ans: Sometimes application of force does not result in a change in the state of motion. This does not mean that force is not applied instead, it means that the force applied is not enough to move the object.

For example, applying pressure on a  wall or a heavy stone and may not move.

9. Why does a rubber sucker stick to the surface of any object?

Ans: The rubber sucker sticks to the surface of any object because of the pressure of the atmosphere that acts on it.

10. Define muscular force. Give examples.

Ans: The force exerted due to the action of the muscles of someone’s body is called muscular force. For example, running, lifting something, jumping, etc.

11. Write a short on the electrostatic force.

Ans: Electrostatic force is the force caused due to attraction or repulsion of electric charges between two particles. This is a non-contact force, therefore it acts when two charged bodies are brought closer to each other. It is also known as Coulomb’s force.

Long Answer Questions                                                                    3 Marks

1. Describe an activity to show that ‘a force can change the state of motion.

Ans: To show that a force can change the state of motion place a rubber ball on any flat surface. Now, push the ball in any direction along the surface. Pushing it again increases its speed while placing a palm in front of it stops its motion and brings the ball to rest. It will move again if a force is applied to it. This proves that a force can change the state of motion.

2. What are the effects of the application of force on an object? Explain.

Ans: The effects of the application of force on an object are:

a. The shape of an object can be changed.

For example, a cricket ball changes its shape temporarily when hit by the bat.

b. The direction of a moving object can be changed.

For example, the direction of the cricket ball changes when hit by the bat.

c. A moving object can be brought to rest.

For example, putting a hand in front of a rolling ball brings it to rest.

d. A stationary object can be brought to motion.

For example, rolling a stationary ball on a plane surface brings it to motion.

e. It can change the speed of an object.

For example, further pushing a rolling ball on a surface in the same direction as its motion increases its speed.

3. Demonstrate an experiment to show that liquids exert pressure on the walls of the container.

Ans: To show that liquids exert pressure on the walls of the container, take a plastic bottle and fix a cylindrical glass tube of a few centimetres near its bottom. To do this, you can simply heat an end of the glass tube and insert it immediately near the bottom of the plastic bottle. Seal any leakage, if present, with molten wax. Now, cover the open end of the glass tube with a thin rubber sheet. Fill half of the bottle with water.

Note that the rubber sheet bulges out due to the pressure applied by water. This proves that liquids exert pressure on the walls of the container.

Class 8 Science Chapter 11 Content

Chapter 11 is all about the fundamental concepts of pressure and force. The chapter starts with the learning force as a result of pushing and pulling along with forces due to an interaction. As one dive deeper into the chapter, you will explore forces, their magnitude, difference between them, qualitative and quantitative analysis. Next, you have the different applications of force. It can change the state of motion and also the shape of an object. Here you get to learn about how to apply force and what are the actions produced by it. Questions from all these sections are there in class 8 force and pressure cbse important questions.

Next, we have contact forces that start with muscular force about how you can push or lift an object easily. Then there is a short introduction on friction after which the section for noncontact forces starts. Here you will get to learn about certain types of forces like magnetic, electrostatic, and gravitational. Further, you have pressure where one will learn about the formula relating to force and pressure which is one of the basic formulas of physics. Then one will get to learn about the application of pressure on gases and liquids. There are various experiments and activities which will help you understand better. Lastly, there is an introduction and activity related to atmospheric pressure. The chapter serves as the foundation for physics in higher classes. And only important questions for class 8 science chapter 11 can help you learn better.

Force And Pressure Class 8 Important Questions Answers – Long Type

There are plenty of class 8 forces and pressure cbse important questions. But here we have picked up some of the important ones.

1. Describe the Various Types of Forces.

Answer: Just by contacting or even from a distance, any force can act on a body. Hence, forces can be further classified into majorly two types: Contact forces and Non Contact forces.

Contact forces are the ones who act on a body as a result of applying indirect or direct physical contact. Generally frictional and muscular force examples of contact forces. The action of muscles tends to produce a force which is known as the muscular force. While, there is a constant force that resists the mutual motion between solid surfaces, material surfaces, or fluid layers that are sliding against each other. It is known as the frictional force or just friction.

Non-contact forces are the exact opposite of the contact once. Here there is no direct contact between the two bodies who are applying forces to each other. The electrostatic, magnetic, and gravitational forces examples falling under this section. The electrostatic force is the force that is exerted by a charged particle on another body. The magnetic force is the force that is exerted by a magnetic material or a magnet on another magnet or similar material. While the gravitational force or simply gravity is the Earth’s attractive force which is exerted upon all its objects.

Force And Pressure Class 8 Important Questions Answers – Short Type

There are plenty of class 8 science chapter 11 important questions. But here we have picked up some of the important ones.

1. Differentiate Between Non-Contact and Contact Forces.

Answer: Non-contact forces are the ones that can be applied to a body without direct or indirect contact. Examples of such forces are magnetic, electrostatic, and gravitational. Contact forces on the other hand are the exact opposite of non-contact forces as they can be applied to a body by coming in direct contact or touching. Examples of such force are muscular and frictional.

2. Why is it More Difficult to Walk with Sharp Heels on Sand Than with Flat Slippers?

Answer: A sharp heeled shoe will have a little area in touch with the sand. It exerts a much greater pressure on the sand. Hence, it is difficult to walk with high heels as the heels sink deeper into the sand due to high pressure. On the other hand, for flat slippers, a larger amount of area is in contact with the sand. It exerts a much lower pressure on the sand. Therefore, it is much easier to walk on the sand with flatter shoes than with high heels.

3. Describe the Force Effects on an Object.

Answer: It is very common in class 8 science chapter 11 important questions. Force can change the shape of an object but also can change the motion state too. It can also change the speed of an object, turn it or change its direction.

4. An Electromagnet is Sticking to a Car at a Junkyard. Name the Forces and Which is Higher.

Answer: The weight of the car or gravitational force acts downward. While the force of magnetic attraction acts in an upward direction. The gravitational force is lesser than the magnetic force.

Chapter 11 Science Class 8 Important Questions

Let’s take a look at some of the important questions which are mentioned below:

• The dough is rolled in the form of a chapati. What is the force that is changing the shape of the dough?

• How to check whether an object is moving slower than the other?

• Two forces are operating in the same direction. What will be the result?

• Why does the ball start moving from rest when it is pushed?

• Discuss the pressure exerted by gases and liquids.

• Why is the electrostatic force a type of non-contact force?

• Why are the wheels of cars and scooters lighter than that of buses and trucks?

• What is the effect of gravitational force on dust?

• Does gravity exist between astronauts in space? Explain.

• It is difficult to burst an inflated balloon with your finger but it becomes easier with the needle. Why?

• How is atmospheric pressure measured?

• Small pieces fall while sieving grains. What is the force pulling them down?

• Why do two thermocol balls move further away from each other when placed closely ? Explain the phenomenon.

Benefits of Force And Pressure Class 8 Important Questions Answers

There are various benefits of force and pressure class 8 important questions as it has been prepared by the best faculties from all over the country. It is an essential study material available for class 8 students. Here all the questions can clear your concepts from the very basics. The solutions will help you understand what to write in the exams to fetch more marks. It helps the student to understand where they need to concentrate and practice more. One gets a clear idea about the question paper pattern. It will help you to prepare for the exams and revise properly for all subparts. Students will understand their time management capabilities on where they require more time to solve. It will increase their efficiency levels to score full marks.

Force And Pressure Class 8 Preparation

The force and pressure class 8 important questions answers will help you with the ultimate preparation to achieve academic supremacy. The force and pressure chapter has a lot of portions and concepts that require clarity. Memorizing would not help because often you get analytical reasoning questions in the exam. The questions will help you understand the syllabus better. Not only does one need to complete the syllabus, but also revise all the concepts. The solutions are there with proper steps and easy language for the students to grasp. The chapter-wise solutions are exam preparation tools. You get to know about the keywords which will fetch you marks. The questions and solutions have been prepared in complete accordance with the current CBSE syllabus by expert professionals. All the solutions are given in the order of the chapter so that a student is not confused about what to study.

Solved Examples

1. Which is a Contact Force?

a. Friction

b. Gravity

c. Electrostatic

d. Magnetic

Answer: Option a.

2. The Force Strength is Expressed by Which Property?

a. Weight

b. Latitudinal Force

c. Longitudinal Force

d. Magnitude

Answer: Option d.

3. What Does Force Change in an Object?

a. Speed

b. Shape

c.  Motion

D. All of the above

Answer: Option d.

4. What Does a Spring Balance Measure?

a. Force

b. Weight

c.  Mass

d. Pressure

Answer: Option b.

5. Two Forces are Acting In Different or Opposite Directions. What is the Net Pressure Across Them?

a. Summation of the forces.

b. The difference between the forces.

c. Both of the above

d. None of the above

Answer: Option b.

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