---
title: "NCERT Solutions for Class 8 Science Chapter 5 Exploring Forces"
url: https://www.swavid.com/science/class/8/chapter/exploring-forces/ncert-solutions
dateModified: 2026-10-07T16:13:41+00:00
---

# NCERT Solutions for Class 8 Science Chapter 5 Exploring Forces

This chapter's questions cover fundamental concepts of forces, including contact and non-contact forces, friction, gravitational force, electrostatic force, weight, mass, and floating and sinking.

Free PDF (8 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-5-exploring-forces-b69e6a29bb.pdf

## Probe and ponder

### Question 1

*3 marks · Short answer*

Why does it feel harder to pedal a bicycle when going uphill than on flat ground?

**Solution**

1. When going uphill, we have to move against the gravitational force acting downwards along the slope.
2. Additionally, muscular force is required to overcome friction and the component of gravity pulling the bicycle back.
3. Therefore, more force is needed to pedal a bicycle uphill compared to riding on flat ground.

**Answer:** It is harder to pedal uphill because we must apply greater muscular force against gravity and friction acting along the slope.

> Common mistake: Thinking that only friction increases uphill, forgetting the role of gravitational force.

### Question 2

*3 marks · Short answer*

Why is it easier to slip on a wet surface?

**Solution**

1. Friction arises due to the irregularities of two surfaces in contact locking into each other.
2. Water acts as a lubricant on a wet surface by filling the minute irregularities between our shoes and the ground.
3. This reduction in interlocking significantly decreases the force of friction, making it easier to slip.

**Answer:** It is easier to slip on a wet surface because water reduces friction by filling the irregularities between the surfaces in contact.

> Common mistake: Stating that water completely removes friction instead of reducing it.

### Question 3

*3 marks · Short answer*

Why do we feel 'light' or like we are 'floating' just after our swing reaches its highest point and begins to come down?

**Solution**

1. When a swing reaches its highest point, it momentarily stops before moving downwards.
2. As it begins to move down with acceleration, the seat of the swing moves away from us slightly faster than our natural downward acceleration under gravity.
3. This reduces the normal contact force exerted by the seat on our body, making us feel weightless or 'floating'.

**Answer:** We feel 'light' at the highest point because the rapid downward acceleration of the swing reduces the contact force exerted by the seat on our body.

> Common mistake: Assuming there is no gravity acting on the person at the top of the swing.

### Question 4

*3 marks · Short answer*

Share your questions

**Solution**

1. Observe natural phenomena related to pushes, pulls, or contact and non-contact forces.
2. Frame a question investigating the cause of a specific force or its effect on motion.
3. Example question: Why does a moving football slow down and eventually stop on a flat grassy field?

**Answer:** Why does a moving football slow down and eventually stop on a flat grassy field?

> Common mistake: Asking a general question not related to forces or motion.

## Keep the curiosity alive

### Question 1

*3 marks · Short answer*

Match items in Column A with the items in Column B.
Column A (Type of force)
(i) Muscular force
(ii) Magnetic force
(iii) Frictional force
(iv) Gravitational force
(v) Electrostatic force
Column B (Example)
(a) A cricket ball stopping on its own just before touching the boundary line
(b) A child lifting a school bag
(c) A fruit falling from a tree
(d) Balloon rubbed on woollen cloth attracting hair strands
(e) A compass needle pointing North

**Part (i)**

1. Muscular force involves the action of muscles in the body, such as lifting an object.

Answer (i): (b) A child lifting a school bag

**Part (ii)**

1. Magnetic force is exerted by magnets, such as a compass needle pointing North.

Answer (ii): (e) A compass needle pointing North

**Part (iii)**

1. Frictional force opposes motion between surfaces in contact, slowing down moving objects.

Answer (iii): (a) A cricket ball stopping on its own just before touching the boundary line

**Part (iv)**

1. Gravitational force is the attractive force exerted by the Earth on objects, pulling them down.

Answer (iv): (c) A fruit falling from a tree

**Part (v)**

1. Electrostatic force is exerted by a charged body, such as a rubbed balloon attracting hair strands.

Answer (v): (d) Balloon rubbed on woollen cloth attracting hair strands

**Answer:** (i)-(b), (ii)-(e), (iii)-(a), (iv)-(c), (v)-(d)

> Common mistake: Confusing magnetic force with gravitational or electrostatic force.

### Question 2

*1 mark · True or false*

State whether the following statements are True or False.
(i) A force is always required to change the speed of motion of an object.
(ii) Due to friction, the speed of the ball rolling on a flat ground increases.
(iii) There is no force between two charged objects placed at a small distance apart.

**Part (i)**

1. A force is always required to change the speed or direction of motion of an object as stated in the textbook.

Answer (i): True

**Part (ii)**

1. Friction opposes motion and decreases the speed of a rolling ball, it does not increase it.
2. Corrected statement: Due to friction, the speed of the ball rolling on a flat ground decreases.

Answer (ii): False

**Part (iii)**

1. Charged objects exert an electrostatic force on each other even when placed at a small distance apart without contact.
2. Corrected statement: There is an electrostatic force between two charged objects placed at a small distance apart.

Answer (iii): False

**Answer:** Statements (i) is True, (ii) is False, (iii) is False.

> Common mistake: Thinking friction can increase the speed of a rolling object.

### Question 3

*3 marks · Short answer*

Two balloons rubbed with a woollen cloth are brought near each other. What would happen and why?

**Solution**

1. When two balloons are rubbed with a woollen cloth, they acquire similar static charges.
2. Like charges repel each other.
3. Therefore, the two balloons will move away from each other.

**Answer:** The two balloons will repel each other and move away because they acquire similar charges upon being rubbed with the same material.

> Common mistake: Thinking that rubbing creates opposite charges on identical objects rubbed with the same material.

### Question 4

*3 marks · Short answer*

When you drop a coin in a glass of water, it sinks, but when you place a bigger wooden block in water, it floats. Explain.

**Solution**

1. When an object is placed in water, it experiences a downward gravitational force (its weight) and an upward buoyant force.
2. A coin sinks because the downward gravitational force acting on it is greater than the upward buoyant force exerted by water.
3. A bigger wooden block floats because the buoyant force acting on it balances its weight or because it is less dense than water.

**Answer:** The coin sinks because its weight is greater than the buoyant force, whereas the wooden block floats.

> Common mistake: Ignoring the role of buoyant force.

### Question 5

*3 marks · Short answer*

If a ball is thrown upwards, it slows down, stops momentarily, and then falls back to the ground. Name the forces acting on the ball and specify their directions.
(i) During its upward motion
(ii) During its downward motion
(iii) At its topmost position

**Part (i)**

1. During upward motion, the gravitational force acts downwards towards the Earth.

Answer (i): Gravitational force acting downwards

**Part (ii)**

1. During downward motion, the gravitational force acts downwards towards the Earth.

Answer (ii): Gravitational force acting downwards

**Part (iii)**

1. At the topmost position, the gravitational force continues to act downwards towards the Earth.

Answer (iii): Gravitational force acting downwards

**Answer:** Gravitational force (gravity) acts downwards in all cases.

> Common mistake: Assuming that no force acts on the ball when it stops momentarily at the topmost position.

### Question 6

*3 marks · Short answer*

A ball is released from the point P and moves along an inclined plane and then along a horizontal surface as shown in the Fig. 5.16. It comes to stop at the point A on the horizontal surface. Think of a way so that when the ball is released from the same point P, it stops (i) before the point A (ii) after crossing the point A.

**Part (i)**

1. Friction is greater on rougher surfaces.
2. If the horizontal surface is made rougher or covered with sand, the increased friction will stop the ball before point A.

Answer (i): Stop the ball before point A by making the horizontal surface rougher.

**Part (ii)**

1. Friction is less on smoother surfaces.
2. If the horizontal surface is made smoother, the reduced friction will allow the ball to travel farther, crossing point A.

Answer (ii): Stop the ball after crossing point A by making the horizontal surface smoother.

**Answer:** To stop the ball before point A, use a rougher surface or place sand; to stop it after point A, use a smoother surface like glass.

> Common mistake: Confusing the effects of rough and smooth surfaces on the distance travelled by a moving object.

### Question 7

*3 marks · Short answer*

Why do we sometimes slip on smooth surfaces like ice or polished floors? Explain.

**Solution**

1. Friction arises due to irregularities in the two surfaces in contact that lock into each other and oppose motion.
2. Smooth surfaces like ice or polished floors have very few irregularities, leading to very little friction.
3. Without sufficient friction, our feet cannot get a proper grip, causing us to slip.

**Answer:** We slip on smooth surfaces because they have very little friction, making it difficult to maintain grip.

> Common mistake: Thinking that smooth surfaces produce more friction.

### Question 8

*3 marks · Short answer*

Is any force being applied to an object in a non-uniform motion?

**Solution**

1. An object in non-uniform motion experiences a continuous change in its speed.
2. A force is always required to change the speed or direction of motion of an object.
3. Therefore, yes, a force must be acting on an object in non-uniform motion.

**Answer:** Yes, a force is being applied to an object in a non-uniform motion to change its speed or direction.

> Common mistake: Stating that no force acts if an object is moving on its own.

### Question 9

*3 marks · Short answer*

The weight of an object on the Moon becomes one-sixth of its weight on the Earth. What causes this change? Does the mass of the object also become one-sixth of its mass on the Earth?

**Solution**

1. Weight is the gravitational force with which a planet pulls an object, and gravity on the Moon is one-sixth of that on Earth.
2. The change in weight is caused by the difference in the gravitational force exerted by the Moon compared to the Earth.
3. Mass is the amount of matter in an object and remains the same everywhere, so the mass does not become one-sixth.

**Answer:** The change in weight is caused by different gravitational forces, but the mass of the object remains unchanged.

> Common mistake: Confusing mass with weight and assuming mass changes with location.

### Question 10

*1 mark · MCQ*

Three objects 1, 2, and 3 of the same size and shape but made of different materials are placed in the water. They dip to different depths as shown in Fig. 5.17. If the weights of the three objects 1, 2, and 3 are $w_1$, $w_2$, and $w_3$, respectively, then

- w1 = w2 = w3
- w1 > w2 > w3
- w2 > w3 > w1
- w3 > w1 > w2

**Solution**

1. When an object floats, its weight is equal to the buoyant force, which depends on the volume of water displaced.
2. From Fig. 5.17, object 1 dips the most, followed by object 2, and object 3 dips the least, meaning object 1 displaces the maximum water and object 3 displaces the minimum.
3. Therefore, the weight of the objects follows the order $w_1 > w_2 > w_3$.

**Answer:** (ii) w1 > w2 > w3

> Common mistake: Confusing depth of immersion with density without relating it to weight.

## Frequently asked questions

### How many total questions are there in NCERT Solutions for Class 8 Science Chapter 5 Exploring Forces?

This chapter contains a total of 14 questions across its exercises. There are 4 questions in the Probe and ponder section and 10 questions in the Keep the curiosity alive section. You can find step-by-step solutions for all of them in the free PDF available on this SwaVid page.

### Which topics do the exercise questions cover in the new NCERT book for Class 8 Science Chapter 5?

The questions cover important concepts like force and uphill motion, friction on wet surfaces, electrostatic charges, and floating and sinking. They also explore weight sensation on a swing, forces acting on a ball in vertical motion, and various types of forces with examples. SwaVid provides detailed answers to help you master all these topics for the 2026-27 session.

### Which question types are the hardest in Class 8 Science Chapter 5 and how should I approach them?

The multiple-choice and conceptual short-answer questions involving forces on a ball in vertical motion or floating and sinking can be challenging. To approach them, first identify all acting forces such as gravity and friction, then apply core principles clearly. Our SwaVid solutions break down each step to make these problems easier to solve.

### How can I write answers to get full marks in Class 8 Science Chapter 5 Exploring Forces?

To secure full marks, write concise answers using proper scientific terminology related to friction, electrostatic charges, and effects of force. Mention the specific conditions given in the problem, such as wet surfaces or vertical motion. Referring to the solved examples in SwaVid's free PDF on this page will guide you on the ideal structure.

### Is the free PDF for Class 8 Science Chapter 5 Exploring Forces based on the new NCERT book available here?

Yes, the complete chapter solutions aligned with the new NCERT book under the NCF 2023 guidelines for the 2026-27 session are available right here. You can download SwaVid's free PDF on this page to access reliable answers for all Probe and ponder and Keep the curiosity alive questions.

## Related pages

- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student