Practise Class 8 Science Chapter 5 – Exploring Forces with this easy NCERT Curiosity worksheet. Includes important questions and revision exercises to strengthen understanding of forces and related scientific concepts and prepare effectively for class tests and exams.
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Exploring Forces
Class 8 Science – Fresh Worksheet
Name: ________________________________
Class & Section: _______________________
Roll No.: ____________ Date: ______________
Instructions: Read each question carefully. Answer in simple and clear sentences. Draw diagrams wherever required.
Section A – Multiple Choice Questions
1. A force is generally described as:
2. The SI unit of force is:
3. Which of the following is a contact force?
4. Friction acts in a direction:
5. Which is a non-contact force?
6. The force exerted by the Earth on an object is called:
7. The SI unit of weight is:
8. Which force acts upward on an object placed in a liquid?
9. Like electric charges:
10. Which instrument is used to measure weight?
Section B – Fill in the Blanks
1. A force is a __________ or __________ on an object.
2. The SI unit of force is __________.
3. The force caused by the action of muscles is called __________ force.
4. Friction is a __________ force.
5. Magnetic force is a __________ force.
6. The force with which the Earth attracts objects is called __________ force.
7. The force exerted by a liquid in the upward direction is called __________ force.
8. The weight of an object is measured in __________.
9. Mass is measured in grams or __________.
10. Similar electric charges __________ each other.
Section C – True or False
1. A force can change the speed of a moving object.
2. A force can change the direction of motion of an object.
3. Friction always acts in the same direction as motion.
4. Muscular force is a contact force.
5. Gravitational force is a non-contact force.
6. Magnetic force can act without physical contact.
7. Mass of an object changes when it is taken from Earth to Moon.
8. Weight is a force.
9. Buoyant force acts downward.
10. Rough surfaces generally produce more friction than smooth surfaces.
Section D – Match the Following
| Column A | Column B |
|---|---|
| 1. Muscular force | A. Pulls objects towards Earth |
| 2. Frictional force | B. Force due to muscles |
| 3. Magnetic force | C. Opposes motion between surfaces |
| 4. Gravitational force | D. Force between magnets |
| 5. Electrostatic force | E. Force due to electric charges |
Section E – Very Short Answer Questions
1. What is force?
2. Write the SI unit of force.
3. Name two contact forces.
4. Name three non-contact forces.
5. What is friction?
6. What is weight?
7. Name the instrument used to measure weight.
8. What is upthrust?
Section F – Short Answer Questions
1. What are the different effects of force on an object?
2. Why is friction called a contact force?
3. Why does a rolling ball eventually stop?
4. Why is friction greater on rough surfaces?
5. What is the difference between contact and non-contact forces?
6. What is the difference between mass and weight?
7. Why does a wooden block float on water while a coin sinks?
Section G – Think and Answer
1. Why do we sometimes slip on smooth surfaces like ice or polished floors?
2. Why does a bicycle slow down when we stop pedalling?
3. Why does a ball thrown vertically upwards come back to the ground?
4. Why does an object feel lighter when it is inside water?
5. Why can a magnet attract an iron object without touching it?
Section H – Application-Based Questions
1. Ragini finds it harder to pedal her bicycle while going uphill. Which force makes the bicycle move downhill and why must she pedal harder?
2. A child pushes a toy car on a smooth floor and another child pushes the same car on a rough floor. On which surface will the car stop sooner? Give a reason.
3. A charged plastic scale attracts small pieces of paper without touching them. Which force is responsible?
4. A spring balance shows a greater stretch when a heavier object is hung from it. What does this tell us?
Section I – Case-Based Questions
Case 1: A student rolls a ball on a table. The ball moves for some distance and then stops. He repeats the activity on a rough cloth and notices that the ball stops sooner.
(a) Which force causes the ball to slow down? (b) On which surface is friction greater? (c) In which direction does friction act?
(a) Which force causes the ball to slow down? (b) On which surface is friction greater? (c) In which direction does friction act?
Case 2: A student hangs a stone from a spring balance. The spring stretches. When a heavier object is hung, the spring stretches more.
(a) What force causes the spring to stretch? (b) What does the spring balance measure? (c) What is the SI unit of weight?
(a) What force causes the spring to stretch? (b) What does the spring balance measure? (c) What is the SI unit of weight?
Section J – Compare and Differentiate
1. Differentiate between mass and weight.
| Mass | Weight |
|---|---|
2. Differentiate between contact force and non-contact force.
| Contact Force | Non-contact Force |
|---|---|
Section K – Higher Order Thinking Questions
1. If friction suddenly disappeared from our surroundings, what problems would we face? Write any three.
2. A ball is thrown upwards. Describe the direction of gravitational force during its upward motion, at the highest point, and during its downward motion.
3. An object has the same mass on Earth and Moon. Why is its weight different?
4. Why can a large ship float on water even though a small iron nail sinks?
Section L – Numerical and Reasoning Practice
1. A spring balance has 5 small divisions between 0 N and 1 N. What is the value of one small division?
2. An object has a mass of 1 kg. Its weight on Earth is approximately 10 N. What will be its weight on the Moon if the weight becomes one-sixth?
3. A spring balance has a range from 0 N to 10 N and 50 equal small divisions. What is the value of one small division?
Section M – Challenge Yourself
1. Two balloons are rubbed with the same woollen cloth and then brought near each other. What happens? Explain why.
2. A ball moves down an inclined plane and then along a horizontal surface. Suggest one way to make it stop before the original stopping point and one way to make it travel beyond that point.
3. Explain why aeroplanes, ships, boats, and high-speed trains are designed with special shapes.
4. Explain why a person feels an upward push when an empty closed bottle is pushed under water.
Answer Key
Section A
- (b) a push or pull
- (c) newton
- (c) Muscular force
- (b) opposite to the direction of motion
- (c) Magnetic force
- (b) gravitational force
- (c) newton
- (c) Buoyant force
- (b) repel each other
- (b) Spring balance
Section B
- push, pull
- newton
- muscular
- contact
- non-contact
- gravitational
- buoyant
- newton (N)
- kilograms (kg)
- repel
Section C
- True
- True
- False
- True
- True
- True
- False
- True
- False
- True
Section D
- Muscular force – B
- Frictional force – C
- Magnetic force – D
- Gravitational force – A
- Electrostatic force – E
Section E
- Force is a push or pull on an object.
- Newton (N).
- Muscular force and frictional force.
- Magnetic, gravitational and electrostatic forces.
- Friction is the force that opposes motion between surfaces in contact.
- Weight is the gravitational force with which the Earth pulls an object.
- Spring balance.
- Upthrust is the upward force applied by a liquid on an object.
Section F
- A force can make an object move, change its speed, change its direction, change its shape, or cause several of these effects.
- Friction acts when two surfaces are in physical contact.
- Friction acts opposite to its motion and slows it down.
- Rough surfaces have more irregularities that oppose motion.
- Contact forces need physical contact; non-contact forces can act from a distance.
- Mass is the amount of matter and remains the same. Weight is gravitational force and can change with gravity.
- The block experiences an upward buoyant force. The coin sinks because its weight is greater than the upward force acting on it.
Section G
- There is less friction on very smooth surfaces, so our feet cannot grip them properly.
- Friction between the bicycle and the ground and air resistance slow it down.
- Earth’s gravitational force pulls the ball downward.
- Water applies an upward buoyant force on the object.
- Magnetic force can act from a distance without physical contact.
Section H
- Gravity pulls the bicycle downhill. Ragini must pedal harder to overcome this effect and move uphill.
- The car stops sooner on the rough floor because friction is greater.
- Electrostatic force.
- The heavier object has greater weight, so it produces a greater stretch in the spring.
Section I
- Case 1: (a) Friction (b) Rough cloth (c) Opposite to the direction of motion.
- Case 2: (a) Gravitational force (b) Weight (force) (c) Newton (N).
Section K
- We would find it difficult to walk, hold objects, write, stop vehicles, and many other activities would become difficult.
- Gravitational force acts downward during upward motion, at the highest point, and during downward motion.
- Mass stays the same, but the Moon has weaker gravity, so the weight becomes smaller.
- A ship displaces a large amount of water and experiences enough buoyant force to float.
Section L
- 1 ÷ 5 = 0.2 N
- 10 ÷ 6 = about 1.67 N
- 10 ÷ 50 = 0.2 N
Section M
- The balloons repel each other because they acquire similar charges, and like charges repel.
- Increase friction to stop it earlier; decrease friction to let it travel farther.
- Their shapes reduce friction caused by air or water.
- Water applies an upward buoyant force on the bottle.
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