NCERT Solutions Class 8 Science Chapter 11

NCERT Solutions for Class 8 Science Chapter 11

Science is both a collection of information and a method of exploration. Science may appear to students in school to be a collection of isolated and unchanging facts contained in a textbook, but this is just half of the picture. Science can also be called a process of discovery that allows us to connect contradictory information to form meaningful and complete views of the natural world.

NCERT Class 8 Science Chapter 11 is Force and Pressure. This chapter will define force and the many categories of forces and also teach you how force is created through practical examples. This is an essential chapter in Physics for students to understand, and the fundamentals are developed in class 8th itself.

Extramarks NCERT solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams.

Students are advised to study from NCERT Solutions present at the end of each chapter to achieve good results in their examinations. Extramarks has come up with a landmark NCERT Solutions for each chapter. The Extramarks experts specially prepare class 8 Science Chapter 11 Solution. NCERT Solutions for Class 8 Science Force and Pressure help you simplify the concepts and help you develop your base of the subject. All of the information you require to get your base clear is present here at Extramarks.

NCERT Solutions for Class 8 Science Chapter 11 proves significantly insightful for the students in their forthcoming board examination. Not just these solutions, students can use the Extramarks website to access several other study tools. NCERT books, CBSE revision notes, CBSE sample papers, CBSE previous year question papers, and other materials are available to students.

Key Topics Covered In NCERT Solutions for Class 8 Science Chapter 11

Mentioned below is a list of primary topics covered in NCERT Solutions for Class 8 Science Chapter 11- Force and Pressure:

What is Force?
Effects of Force
Types of Force
What can a force do?
Thrust and Pressure
Atmospheric Pressure

Let us dig into Extramarks detailed notes on each sub-topic in NCERT Solutions for Class 8 Science Chapter 11- Force and Pressure.

What is Force?

A push or pull on an object is known as a force in science. Force is created when two objects are in contact. The intensity and direction of force are equally important. A force’s strength is measured in magnitude. A change in the condition or direction of motion of a body is caused by force. Extramarks NCERT Solutions for Class 8 Science Chapter 11 focuses on the various concepts of force.

The Push and Pull of an Object

The force, for example, has been described as an interaction that, if unopposed, modifies the motion of an object. When we look at this sentence more thoroughly, we can see how push-pull plays a part. A pull is a force that completely alters the direction of an item towards you. On the other hand, if it travels away, it is a push. When two objects interact with each other, this force is sometimes described as a push or a pull on the object. As a result, each force is essentially a push or a pull. Elastic and spring forces are additional examples of forces. It will usually resist and react when you press on it or spring back with the same force.

Examples of Push:

  • Pushing a vehicle when it breaks down
  • Pushing a chair from one place to another

Examples of Pull:

  • Pulling a toy from a child’s hand
  • Pulling a door 

Effects of Force

Extramarks NCERT Solutions for Class 8 Science Chapter 11 explains various effects of force as follows:

  • When two things interact with each other, they produce a force. If we take football as an example, it will not move unless someone kicks it. So, due to the interaction between the person and the football, a force is created that causes it to move.
  • The magnitude as well as the direction of a force are both known as its strength. The applied force might be great, minor, or equal in magnitude. In addition, the forces might be used in the same direction or opposite directions. These alter the force’s effect on the item. For example, it is easier to move a heavy thing with two individuals pushing it in the same direction than with two persons pushing it in different directions.
  • A force can cause an object’s speed, direction, or both. This indicates that the object’s state of motion has changed. For example, if we imagine a football being kicked by a player, the kick causes the stationary ball to move in the direction it is being kicked. Likewise, the speed of an item is determined by the amount of force applied to it.
  • An object’s form may change due to a force operating on it. For example, the dough may be rolled into chapatis using the power and rolling.
  • A force can act on an item while it is in touch with it or when it is not.

Types of Force

Depending on whether the force operating on the item is in touch with it, there are two sorts of forces. They can also be classified based on some contact or non-contact force being applied.

Contact Force

A contact force is a force that operates on an object when it comes into touch with the body. The point of application of force, also known as the point of contact, is where force is applied to an object. The following are the several types of contact forces:

  • Muscular Force: A muscular force is a force exerted as a result of the action of our body’s muscles. Some of our primary functions, such as breathing and digesting, rely on muscle effort. Buffalo, camels, and horses use their muscular force to do tasks for humans, such as ploughing, pulling, and carrying the cargo.
  • Frictional Force: A frictional force resists the motion of an item and always acts in the opposite direction of the object’s motion. This may be seen when we stop rowing and the boat stops moving. The frictional force between the boat and the water causes this.

Non-Contact Force

A non-contact force does not entail any physical contact between the two objects on which it acts. The following are the several types of non-contact forces:

  • Magnetic Force: A magnetic force is a force produced by a magnet on items made of iron, steel, cobalt, or nickel without being in touch with them.
  • Electrostatic Force: An electrostatic force is a force exerted by a charged body on another charged or uncharged entity. If we bring two straws rubbed with paper charged near one another, it may result in the repulsion of comparable charges and attraction of opposing charges if we get a charged straw near an uncharged straw.
  • Gravitational Force: The gravitational force is an attracting force exerted by everything in the world on another object.
  • Nuclear Force: All of the particles in the nucleus are affected by the nuclear force. Precisely, between two neutrons, two protons, and a neutron and a proton. In all circumstances, it is a powerful force. The force maintains the nucleus together by counteracting the massive repulsive force between positive protons.

Extramarks NCERT Solutions for Class 8 Science Chapter 11 describes the types of Forces briefly. For any other information relating to force, refer to the Extramarks website and use the abundant resources present.

What can a force do?

Velocity

The size and direction of the item are both given as vector values. – Examples include velocity, displacement, weight, momentum, force, and acceleration. To discover the resulting component operating on a body, vectors are utilised. When numerous forces work on a body, the net force acting on the item can be resolved into a single component. When a force is applied at an angle to the horizontal, vectors are also relevant.

Application of Force

A force is an effort that alters the status of a stationary or moving item. For example, it may modify the direction and velocity of an item. Force may also change an object’s form.

State of Motion

The speed of an object with regards to its direction is called its velocity. 

Based on the abovementioned definition, inertia may be 

defined as the tendency of an object to resist any changes in its velocity.

An object at rest has zero velocity and will remain at zero velocity in the absence of an imbalanced force; it will not change its state of motion (i.e., velocity). In the absence of an imbalanced force, an object in action with a velocity of 2 m/s, East, will continue in motion with a velocity of 2 m/s, East; it will continue to retain its state of motion (i.e. velocity). Objects are resistant to changes in velocity.

The above-stated points describe the things force can perform and under what conditions per Extramarks NCERT Solutions for Class 8 Science Chapter 11. For more details on the topic, refer to the Extramarks website.

Thrust and Pressure

Extramarks NCERT Solutions for Class 8 Science Chapter 11 explains another important topic of Thrust and Pressure. The unit force acting on a surface per unit area is known as pressure. The following is a definition of the connection between pressure and force:

Pressure= Force divided by the area on which it acts.

Pushing a nail into a wooden board with the pointed end rather than the head is more accessible because the smaller area puts more pressure for the same amount of effort, and the nail enters into the wood with one push.

In the SI system, the unit of pressure is Newton per square metre, which is equivalent to 1 Pascal (Pa).

Distribution of Pressure

  • When a force is applied to a smaller area, it exerts more pressure than when the same force is applied to a broader area.
  • Porters, for example, wear a circular cloth over their heads to increase surface area and relieve pressure.
  • A sharp knife slices better because more pressure is applied across a smaller area.

Pressure in Fluids

The pressure produced by a fluid (gases or liquids) in a container is transferred evenly across the container’s walls.

Upthrust

The Buoyant force or Upthrust is the upward force exerted by a fluid on an object surrounded by that fluid. 

Atmospheric Pressure

The air that envelops the world is called the atmosphere. Our atmosphere reaches many kilometres above sea level. Atmospheric pressure is the result of the weight of the air. However, we are oblivious to the immense air pressure that surrounds us. This is because the fluid pressure within our bodies balances out the air pressure around us.

Gaseous Pressure

Gases put uniform pressure on the container’s walls in all directions.

Extramarks NCERT Solutions for Class 8 Science Chapter 11 explains the concept of Atmospheric Pressure. To gain more information on and around the topic, refer to the Extramarks website. This website is a house to quality study material.

NCERT Solutions for Class 8 Science Chapter 11 Exercise and Solutions

Extramarks is a powerhouse of good study material. Students can take complete advantage of all the quality study material. The experts of Extramarks take care of the students’ needs while compiling the study material. Click on the below links to view NCERT Solutions for Class 8 Science Chapter 11: 

  • Class 8 Science Chapter 11: Very Short Answer Type Questions
  • Class 8 Science Chapter 11: Short Answer Type Questions
  • Class 8 Science Chapter 11: Long Answer Type Questions

Students may access NCERT Solutions for Class 8 Science Chapter 11 and other chapters by clicking here. In addition, students can also explore NCERT Solutions for other classes below.

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By getting access to Extramarks, NCERT Solutions for Class 8 Science Chapter 11, students can quickly grasp all the concepts of Force and Pressure.

Key Features of NCERT Solutions for Class 8 Science Chapter 11

Extramarks NCERT solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams.

Students should thoroughly go through all the concepts to score well in their forthcoming examination. NCERT Solutions provided by Extramarks makes it easier for students to prepare well. In addition, NCERT Solutions for Class 8 Science Chapter 11 provides detailed information about the chapter, which helps students prepare. Following are some of the reasons why should you choose Extramarks:

  • Not just retaining, these solutions help students comprehend the fundamentals of the chapter.
  • It is time-saving for the students to go through these solutions.
  • While practising these solutions, students also get an idea of the writing pattern to be followed in the examination.

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

Ans-

Examples of Push:

  1. A suitcase at rest is pushed to move from one place to another. This changes the state of motion of the suitcase.
  2. A football is pushed by a player using his foot.This changes the state of motion of the football.

Examples of Pull:

  1. To open a drawer, it is pulled out. This changes the state of motion of the drawer.
  2. Rope is pulled to draw water from a well. This changes the state of motion of the water bucket.

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

Ans-

  1. Squeezing of tin container.
  2. Pressing clay by hands.

Q.3 Fill in the blanks in the following statements.

(a) To draw water from a well we have to ___ on 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-

(a) To draw water from a well we have to pull on the rope.
(b) A charged body attracts an uncharged body towards it.
(c) To move a loaded trolley we have to either push or pull it.
(d) The north pole of a magnet repels the north pole of another magnet.

Q.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, non-contact, gravity, friction, shape, attraction

(a) To stretch the bow, the archer applies a force that causes a change in its __________.
(b) The force applied by the archer to stretch the bow is an example of __________ force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a __________ force.
(d) While the arrow moves towards its target, the forces acting on it are due to __________ and that due to __________ of air.

Ans-

(a) To stretch the bow, the archer applies a force that causes a change in its shape.
(b) The force applied by the archer to stretch the bow is an example of muscular force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a contact force.
(d) While the arrow moves towards its target, the forces acting on it are due to gravity and that due to friction of air.

Q.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-

(a) Muscular force is used in squeezing a piece of lemon. This muscular force acts on the lemon. Thus, the shape of the lemon gets changed.
(b) To take out paste from a toothpaste tube, muscular force is used and it acts on the toothpaste tube. Thus, the shape of the tube gets changed.
(c) The suspended load exerts a force on the spring and pushes the spring in downward direction. Thus, the spring gets stretched and its shape gets changed.
(d) In a high jump, an athlete pushes the ground with his feet and exerts a muscular force on the ground. As a result, he can jump over the bar. Thus, his state of motion gets changed.

Q.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 uses muscular force when he hammers on a hot piece of iron. Due to this muscular force, the shape of the iron gets changed and iron piece can be given a desired shape.

Q.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 gets charged when it is rubbed with a piece of synthetic cloth. A charged body attracts an uncharged body. When this balloon is pressed against a wall, it sticks to the wall. The force acting between the charged balloon and the wall is the electrostatic force due to which it was stuck.

Q.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-

When we hold a plastic bucket filled with water above the ground, there are two forces act on it. First is the gravitational force which acts downwards and second is the muscular force exerted by us which acts in the upward direction. The two forces are equal in magnitude but opposite in direction. Hence, the net force on the bucket is zero. Therefore, there is no change in its state of motion.

Q.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-

  1. The force of gravity which tries to pull the rocket downwards.
  2. The force of friction due to earth’s atmosphere, which opposes the motion of the rocket.

Q.10 When we press the bulb of a dropper with its nozzle kept in water, 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) gravity of the earth.
(c) shape of rubber bulb.
(d) atmospheric pressure.

Ans-

The correct option is (d).

Explanation: When the air filled in the nozzle is removed, the atmospheric pressure, which is acting on the water, forces the water to fill the nozzle of the dropper.

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FAQs (Frequently Asked Questions)
1. In simple language, please provide a short list of the 11th chapter of Class 8 Science?

The title of Chapter 11 of Class 8 Science refers to the introduction of students to the concepts of force and pressure. Students learn the definitions of force and pressure, recognising that the concepts are complex and the material created above by the Extramarks SMEs help develop this understanding. Force is defined as any push or pull that operates on the surface of an object at the Class 8 level. The force is the label given to any push or pull that works on an item. As a result, the force operating on a unit area of space is called pressure. These are the chapter’s basic concepts.

2. Why are NCERT Solutions helpful in learning Chapter 11 of Science for Class 8?

Extramarks NCERT Solutions are helpful since they present accurate information and ideas in their simplest form. This is why students find it very easy and convenient to use Extramarks Solutions and notes. Specialists with several years of subject background have created these solutions, and students will benefit from utilising them because Chapter 11 of Class 8 Science is all about force. If students read these notes carefully a few times, using these solutions, not only will they comprehend well, but they will also score much higher in their exams.