Test your knowledge with this free online TNPSC Physics Force Test 3 on Contact and Non-Contact Forces. Answer important MCQs covering the key concepts of friction, tension, normal reaction, muscular, magnetic, electrostatic and gravitational forces and strengthen your understanding of Physics for the TNPSC General Science examination.
Note: Once you complete the test, go through the detailed explanations below to understand the answers and improve your preparation.
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TNPSC Physics Force Test 3: Contact and Non – Contact Forces (Important Details & Quick Revision)
In this section, you will find detailed explanations for every question in the TNPSC Physics Force Test 3. Understand why the correct answer is right and how the other options differ, with clear explanations of contact and non-contact forces. These explanations will help you strengthen your concepts and prepare confidently for TNPSC General Science examinations. The Quick Revision section at the end will help you review important concepts and key facts quickly before your TNPSC General Science examination.
1. Which of the following is a contact force?
- A. Frictional force
- B. Gravitational force
- C. Magnetic force
- D. Electrostatic force
Correct Answer: A. Frictional force
Explanation:
Frictional force is a contact force because it acts between two surfaces that are in physical contact with each other. It opposes the relative motion or the tendency of one surface to move over another.
Friction depends on the nature of the surfaces in contact. It helps us perform many everyday activities, such as walking without slipping, holding objects firmly and applying brakes to stop vehicles.
Why the Other Options Are Incorrect:
- B. Gravitational force: It is a non-contact force of attraction between objects with mass. Earth’s gravity pulls objects towards the ground without requiring direct contact.
- C. Magnetic force: It is a non-contact force that can attract magnetic materials without touching them. Magnets can also attract or repel one another.
- D. Electrostatic force: It is a non-contact force that acts between electrically charged objects. A rubbed plastic comb can attract small pieces of paper without touching them first.
Example: When a student slides a book across a table, friction acts between the book and the table, opposing the book’s motion. This demonstrates why frictional force is classified as a contact force.
So, frictional force is a contact force, while gravitational, magnetic and electrostatic forces are non-contact forces.
2. Which force acts between the Earth and all objects near its surface?
- A. Tension force
- B. Frictional force
- C. Gravitational force
- D. Muscular force
Correct Answer: C. Gravitational force
Explanation:
Gravitational force is the force of attraction between any two objects that have mass. Earth attracts objects near its surface towards its centre due to gravity. This force gives objects weight and causes them to fall towards the ground when dropped. Gravitational force acts even when objects are not in physical contact with the Earth.
Why the Other Options Are Incorrect:
- A. Tension force: It is a contact force transmitted through a stretched rope, string or cable when it pulls on an object.
- B. Frictional force: It is a contact force that acts between surfaces in contact and opposes their relative motion or tendency to move.
- D. Muscular force: It is a contact force produced by the muscles of humans or animals to push, pull or lift objects.
Example: When you drop a ball from your hand, it falls towards the ground because Earth’s gravitational force pulls it downward.
So, gravitational force attracts objects with mass, including objects near Earth’s surface.
3. Which of the following is a non-contact force?
- A. Normal reaction force
- B. Tension force
- C. Magnetic force
- D. Frictional force
Correct Answer: C. Magnetic force
Explanation:
A non-contact force can act between objects without them physically touching each other. Magnetic force is a non-contact force because a magnet can attract or repel another magnet and attract magnetic materials, such as iron, from a distance. The force acts through the magnetic field surrounding the magnet.
Why the Other Options Are Incorrect:
- A. Normal reaction force: It is a contact force exerted by a surface on an object touching it. For example, a table exerts an upward normal reaction force on a book resting on it.
- B. Tension force: It is a contact force transmitted through a stretched rope, string or cable that pulls an attached object.
- D. Frictional force: It is a contact force that develops between surfaces in contact and opposes their relative motion or tendency to move.
Example: When a magnet attracts an iron nail without touching it, the magnetic force acts across the gap. This demonstrates a non-contact force.
So, magnetic force is a non-contact force, while normal reaction, tension and frictional forces require physical contact.
4. The force exerted by human muscles while lifting a load is called:
- A. Electrostatic force
- B. Muscular force
- C. Magnetic force
- D. Gravitational force
Correct Answer: B. Muscular force
Explanation:
Muscular force is the force produced by the muscles of humans and animals. It is used to perform activities such as lifting, pushing, pulling and carrying objects. Muscular force is classified as a contact force because the force is applied through physical contact with the object, either directly or through an object being held.
When a person lifts a load, the muscles in their arms and other parts of the body contract to produce the force needed to raise it against gravity.
Why the Other Options Are Incorrect:
- A. Electrostatic force: It acts between electrically charged objects and does not require physical contact.
- C. Magnetic force: It acts between magnets or magnetic materials and can work without direct contact.
- D. Gravitational force: It is the force of attraction between objects with mass. Earth’s gravity pulls the load downward rather than lifting it.
Example: When a person lifts a schoolbag from the floor and places it on a desk, the person uses muscular force to raise the bag.
So, muscular force is produced by the muscles of humans and animals to perform physical activities.
5. Friction acts mainly:
- A. Between surfaces in contact
- B. Between electrically charged bodies only
- C. Between magnetic poles only
- D. Only in liquids
Correct Answer: A. Between surfaces in contact
Explanation:
Frictional force acts between surfaces that are in contact with each other. It opposes the relative motion or the tendency of one surface to move over another. Even surfaces that appear smooth have tiny irregularities that interact when they touch, contributing to friction.
Friction can act between solid surfaces and also between objects moving through fluids, such as air and water. Therefore, it is not limited to liquids.
Why the Other Options Are Incorrect:
- B. Between electrically charged bodies only: This describes electrostatic interactions, not friction. Friction can occur between many types of surfaces, whether electrically charged or not.
- C. Between magnetic poles only: Magnetic force acts between magnets and magnetic materials. Friction does not require magnetic poles.
- D. Only in liquids: Friction is not limited to liquids. It acts between solid surfaces and also occurs as resistance when objects move through fluids.
Example: When you push a book across a table, friction acts between the book and the table, opposing the book’s movement.
So, friction acts between surfaces in contact and can also occur when objects move through fluids.
6. Which force is responsible for the attraction between a magnet and an iron nail?
- A. Gravitational force
- B. Magnetic force
- C. Electrostatic force
- D. Tension force
Correct Answer: B. Magnetic force
Explanation:
Magnetic force is responsible for the attraction between a magnet and an iron nail. A magnet produces a magnetic field around it, which can exert a force on magnetic materials such as iron. This force can act even when the magnet and the nail are separated by a small distance, so direct physical contact is not necessary.
Magnetic force is classified as a non-contact force. Depending on the materials and the situation, magnetic forces can cause attraction or repulsion.
Why the Other Options Are Incorrect:
- A. Gravitational force: It is the force of attraction between objects with mass. Earth’s gravity pulls the nail downward, but it is not responsible for the magnet attracting the nail.
- C. Electrostatic force: It acts between electrically charged objects. It is not the main force responsible for the attraction between an ordinary magnet and an iron nail.
- D. Tension force: It is transmitted through a stretched rope, string or cable. It does not cause a magnet to attract an iron nail.
Example: When a magnet is brought near an iron nail, the nail moves towards the magnet even before they touch. This happens because of magnetic force.
So, magnetic force is a non-contact force that can attract magnetic materials such as iron.
7. A charged comb attracting small pieces of paper demonstrates:
- A. Magnetic force
- B. Electrostatic force
- C. Frictional force
- D. Muscular force
Correct Answer: B. Electrostatic force
Explanation:
When a plastic comb is rubbed against dry hair, it can gain an electric charge due to the transfer of electrons. The charged comb produces an electric field around it. When the comb is brought near small pieces of paper, it causes charges within the paper to redistribute slightly, producing an attraction. This attraction is due to electrostatic force.
Electrostatic force is a non-contact force because the charged comb can attract the paper without touching it. The paper does not need to be electrically charged overall for this attraction to occur.
Why the Other Options Are Incorrect:
- A. Magnetic force: It acts between magnets and magnetic materials. A charged comb attracting ordinary paper is not an example of magnetic force.
- C. Frictional force: It acts between surfaces in contact and opposes their relative motion. It is not the force responsible for attracting the paper towards the charged comb.
- D. Muscular force: It is produced by the muscles of humans or animals to push, pull or lift objects. It does not explain the attraction between the charged comb and the paper.
Example: After rubbing a plastic comb against dry hair, bring it close to tiny pieces of paper. The paper pieces may jump towards the comb due to electrostatic attraction.
So, electrostatic force can attract objects without direct physical contact.
8. Which force acts through a stretched string or rope?
- A. Normal reaction force
- B. Gravitational force
- C. Tension force
- D. Electrostatic force
Correct Answer: C. Tension force
Explanation:
Tension force is the pulling force transmitted through a stretched string, rope or cable when forces act on its ends. It acts along the length of the string or rope and pulls the objects attached to it. A rope can transmit tension while it is stretched, but it cannot push an object in the same way a rigid rod can.
Tension is classified as a contact force because the rope or string must be in contact with the object to pull it.
Why the Other Options Are Incorrect:
- A. Normal reaction force: It is the support force exerted by a surface on an object in contact with it. For example, a floor exerts a normal reaction force on a person standing on it.
- B. Gravitational force: It is the force of attraction between objects with mass and can act without physical contact.
- D. Electrostatic force: It acts between electrically charged objects and does not require a stretched string or rope.
Example: When a bucket is lifted from a well using a stretched rope, the rope transmits tension to pull the bucket upward.
So, tension force is transmitted through a stretched string, rope or cable.
9. Which of the following forces can act without physical contact?
- A. Electrostatic force
- B. Frictional force
- C. Tension force
- D. Normal reaction force
Correct Answer: A. Electrostatic force
Explanation:
Electrostatic force acts between electrically charged objects. It can produce attraction between opposite charges and repulsion between like charges without the objects physically touching. The force acts through the electric field surrounding charged objects.
Unlike contact forces, electrostatic force does not require direct contact between the interacting objects. This makes it a non-contact force.
Why the Other Options Are Incorrect:
- B. Frictional force: It acts between surfaces in contact and opposes their relative motion or tendency to move.
- C. Tension force: It is transmitted through a stretched string, rope or cable that is in contact with the objects it pulls.
- D. Normal reaction force: It is exerted by a surface on an object touching it, usually perpendicular to the surface.
Example: When a rubbed plastic comb attracts small pieces of paper without touching them, electrostatic force acts between the comb and the paper.
So, electrostatic force can act without physical contact, whereas frictional, tension and normal reaction forces require contact.
10. The force exerted by a surface on an object perpendicular to the surface is called:
- A. Frictional force
- B. Normal reaction force
- C. Magnetic force
- D. Muscular force
Correct Answer: B. Normal reaction force
Explanation:
The normal reaction force is the support force exerted by a surface on an object in contact with it. The word “normal” means perpendicular to the surface. Therefore, this force acts at a right angle (90°) to the surface at the point of contact.
When an object rests on a table, the table exerts an upward normal reaction force on the object. This force supports the object and prevents it from passing through the table. The normal reaction force is a contact force because the object must touch the surface for this force to act.
Why the Other Options Are Incorrect:
- A. Frictional force: It acts along the surface of contact and opposes relative motion or the tendency of one surface to move over another.
- C. Magnetic force: It can act between magnets or magnetic materials without direct physical contact.
- D. Muscular force: It is produced by the muscles of humans or animals to push, pull or lift objects.
Example: A book resting on a horizontal table experiences an upward normal reaction force from the table, perpendicular to its surface.
So, the normal reaction force acts perpendicular to the surface in contact with an object.
11. Which of the following is an example of a contact force?
- A. Electrostatic attraction between charges
- B. Magnetic attraction between magnets
- C. Gravitational attraction between the Earth and the Moon
- D. Friction between a tyre and a road
Correct Answer: D. Friction between a tyre and a road
Explanation:
Friction between a tyre and a road is an example of a contact force because the tyre and the road are in physical contact. Friction acts at the contact surface and helps the tyre grip the road. This grip allows vehicles to accelerate, turn and brake safely.
Without sufficient friction, a tyre may slip on the road, making it difficult for the driver to control the vehicle. Friction can oppose slipping or relative motion between the tyre and the road.
Why the Other Options Are Incorrect:
- A. Electrostatic attraction between charges: It is a non-contact force that acts between electrically charged objects without requiring them to touch.
- B. Magnetic attraction between magnets: It is a non-contact force that can act between magnets separated by a distance.
- C. Gravitational attraction between the Earth and the Moon: It is a non-contact force that acts between objects with mass across space.
Example: When a cyclist applies the brakes, friction between the brake components and the wheel helps slow the bicycle. Friction between the tyres and the road also helps the bicycle maintain grip.
So, friction between a tyre and a road is a contact force because the surfaces interact at their point of contact.
12. Which force keeps the Moon in orbit around the Earth?
- A. Magnetic force
- B. Tension force
- C. Gravitational force
- D. Frictional force
Correct Answer: C. Gravitational force
Explanation:
Gravitational force is the force of attraction between objects that have mass. The Earth attracts the Moon through gravity, and this gravitational force provides the centripetal force needed to keep the Moon moving in its orbit around the Earth.
The Moon has forward motion, but Earth’s gravitational pull continually changes the direction of that motion. As a result, the Moon follows a curved path around the Earth instead of moving away in a straight line. Gravity acts across the space between the Earth and the Moon, so physical contact is not required.
Why the Other Options Are Incorrect:
- A. Magnetic force: It acts between magnets and magnetic materials. It is not responsible for keeping the Moon in its orbit around the Earth.
- B. Tension force: It is transmitted through a stretched rope, string or cable. No physical rope or string connects the Earth and the Moon.
- D. Frictional force: It acts between surfaces in contact or provides resistance when objects move through fluids. It does not keep the Moon in orbit around the Earth.
Example: The Moon continues to revolve around the Earth because Earth’s gravitational attraction continually changes the direction of the Moon’s motion.
So, gravitational force keeps the Moon in orbit around the Earth without requiring physical contact.
13. Which force acts between electrically charged bodies?
- A. Electrostatic force
- B. Normal reaction force
- C. Muscular force
- D. Tension force
Correct Answer: A. Electrostatic force
Explanation:
Electrostatic force is the force of attraction or repulsion between electrically charged bodies. Unlike contact forces, it can act even when the charged bodies are not physically touching. Opposite charges attract each other, while like charges repel each other.
Why the Other Options Are Incorrect:
- B. Normal reaction force: This is the support force exerted by a surface on an object in contact with it.
- C. Muscular force: This force is produced by the muscles of humans or animals, such as when lifting a bag.
- D. Tension force: This force acts through a stretched string, rope or cable.
Example: When a plastic comb is rubbed against dry hair and brought near small pieces of paper, the paper pieces may be attracted to the comb due to electrostatic force.
Electrostatic force acts between charged bodies without physical contact, making it a non-contact force.
14. Which force is produced by the interaction between surfaces in contact?
- A. Magnetic force
- B. Gravitational force
- C. Electrostatic force
- D. Frictional force
Correct Answer: D. Frictional force
Explanation:
Frictional force is produced when two surfaces are in contact and oppose their relative motion or the tendency to move relative to each other. It helps us walk without slipping, hold objects firmly and stop moving vehicles. The amount of friction depends on factors such as the nature of the surfaces and how strongly they are pressed together.
Why the Other Options Are Incorrect:
- A. Magnetic force: This force acts between magnets or magnetic materials and can act without physical contact.
- B. Gravitational force: This is the force of attraction between objects that have mass. It acts over a distance.
- C. Electrostatic force: This force acts between electrically charged bodies and can act without physical contact.
Example: When you apply the brakes on a bicycle, friction helps slow down the bicycle. Friction between your shoes and the ground also helps you walk without slipping.
Frictional force is a contact force because it acts between surfaces that are touching.
15. Which of the following is a non-contact force?
- A. Tension force
- B. Electrostatic force
- C. Muscular force
- D. Normal reaction force
Correct Answer: B. Electrostatic force
Explanation:
A non-contact force acts on an object without requiring direct physical contact. Electrostatic force acts between electrically charged bodies. Depending on the types of charges, the force can cause attraction or repulsion. For example, a positively charged body and a negatively charged body attract each other.
Why the Other Options Are Incorrect:
- A. Tension force: This force is transmitted through a stretched string, rope or cable, so it involves physical contact.
- C. Muscular force: This force is produced by the muscles of humans or animals and is applied through physical contact.
- D. Normal reaction force: This force is exerted by a surface on an object touching it, usually perpendicular to the surface.
Example: When a charged balloon attracts small pieces of paper without directly touching them at first, electrostatic force causes the attraction.
Therefore, electrostatic force is a non-contact force, while tension, muscular force and normal reaction force are contact forces.
16. A person pushing a box on the floor mainly applies:
- A. Gravitational force
- B. Electrostatic force
- C. Muscular force
- D. Magnetic force
Correct Answer: C. Muscular force
Explanation:
Muscular force is the force produced by the muscles of humans or animals. When a person pushes a box, the muscles in the arms and other parts of the body produce the force needed to move it. Muscular force is a contact force because the person must physically touch the box to push it.
Why the Other Options Are Incorrect:
- A. Gravitational force: This force attracts objects that have mass towards each other. Earth’s gravity pulls the box towards the ground.
- B. Electrostatic force: This force acts between electrically charged bodies and can act without physical contact.
- D. Magnetic force: This force acts between magnets or magnetic materials and can act without physical contact.
Example: When you push a heavy cupboard to move it from one place to another, you apply muscular force.
Muscular force is a contact force because it is applied through physical contact with the object.
17. Which force acts between a body and the surface supporting it?
- A. Magnetic force
- B. Electrostatic force
- C. Tension force
- D. Normal reaction force
Correct Answer: D. Normal reaction force
Explanation:
Normal reaction force is the support force exerted by a surface on an object resting on or pressing against it. It acts perpendicular to the surface at the point of contact. For example, when a book rests on a horizontal table, the table exerts an upward normal reaction force on the book, supporting it against gravity.
Why the Other Options Are Incorrect:
- A. Magnetic force: This force acts between magnets or magnetic materials and does not require direct contact.
- B. Electrostatic force: This force acts between electrically charged bodies and can act over a distance.
- C. Tension force: This force acts through a stretched string, rope or cable.
Example: When you sit on a chair, the chair exerts an upward normal reaction force on your body to support your weight.
Normal reaction force is a contact force because the supporting surface must be in contact with the object.
18. Which force acts between a moving vehicle and the road surface?
- A. Gravitational force
- B. Frictional force
- C. Electrostatic force
- D. Magnetic force
Correct Answer: B. Frictional force
Explanation:
Frictional force acts between the tyres of a vehicle and the road surface when they are in contact. It provides the grip needed for a vehicle to start moving, turn and brake safely. Without sufficient friction, the tyres may slip, making it difficult for the driver to control the vehicle.
Why the Other Options Are Incorrect:
- A. Gravitational force: This force pulls the vehicle towards Earth and helps keep it on the road, but it is not the force responsible for the grip between the tyres and the road.
- C. Electrostatic force: This force acts between electrically charged bodies.
- D. Magnetic force: This force acts between magnets or magnetic materials.
Example: When a car moves on a road, friction between the tyres and the road helps the tyres grip the surface. During braking, friction also helps the vehicle slow down.
Frictional force is a contact force because the tyres and the road surface interact while touching.
19. Which of the following is not a contact force?
- A. Frictional force
- B. Tension force
- C. Electrostatic force
- D. Normal reaction force
Correct Answer: C. Electrostatic force
Explanation:
A contact force requires physical contact between interacting objects. Electrostatic force is different because it acts between electrically charged bodies even when they are separated by a distance. It can produce attraction between opposite charges and repulsion between like charges.
Why the Other Options Are Incorrect:
- A. Frictional force: It acts between surfaces in contact and opposes relative motion or the tendency to move.
- B. Tension force: It is transmitted through a stretched string, rope or cable.
- D. Normal reaction force: It is exerted by a supporting surface on an object in contact with it.
Example: A charged comb can attract small pieces of paper without touching them initially. This attraction is caused by electrostatic force.
Electrostatic force is a non-contact force, whereas friction, tension and normal reaction are contact forces.
20. Which statement is scientifically correct?
- A. Magnetic force always requires physical contact.
- B. Gravitational force acts only on moving bodies.
- C. Friction acts without contact between surfaces.
- D. Electrostatic force can act without physical contact.
Correct Answer: D. Electrostatic force can act without physical contact.
Explanation:
Electrostatic force acts between electrically charged bodies and does not require them to touch. It can attract or repel charged objects depending on the type of charge they carry. This is an example of a non-contact force.
Why the Other Options Are Incorrect:
- A. Magnetic force always requires physical contact: Incorrect because magnetic force can act over a distance, such as when a magnet attracts an iron nail without touching it.
- B. Gravitational force acts only on moving bodies: Incorrect because gravity acts between objects that have mass whether they are moving or at rest.
- C. Friction acts without contact between surfaces: Incorrect because friction between solid surfaces requires them to be in contact.
Example: When a rubbed balloon attracts small pieces of paper without touching them initially, electrostatic force acts across the gap between the balloon and the paper.
Electrostatic, magnetic and gravitational forces are non-contact forces, while friction, tension, muscular force and normal reaction force are contact forces.
Quick Revision Table – Contact and Non-Contact Forces
| Key Concept | Correct Answer | Example |
|---|---|---|
| Contact force | Frictional force | A book sliding across a table experiences friction. |
| Force between Earth and objects | Gravitational force | An apple falls towards the ground. |
| Non-contact force | Magnetic force | A magnet attracts an iron nail without touching it. |
| Force produced by muscles | Muscular force | A person lifts a school bag. |
| Force between surfaces in contact | Frictional force | Shoes grip the ground while walking. |
| Attraction between a magnet and an iron nail | Magnetic force | A magnet attracts an iron nail. |
| Charged comb attracting paper | Electrostatic force | A rubbed plastic comb attracts small paper pieces. |
| Force through a stretched rope | Tension force | A rope supports a bucket being lifted from a well. |
| Force acting without physical contact | Electrostatic force | A charged balloon attracts small paper pieces. |
| Force perpendicular to a supporting surface | Normal reaction force | A table supports a book resting on it. |
| Contact force between a tyre and road | Frictional force | Tyres grip the road when a vehicle moves. |
| Force keeping the Moon in orbit | Gravitational force | Earth’s gravity keeps the Moon in orbit. |
| Force between charged bodies | Electrostatic force | Two similarly charged objects repel each other. |
| Force caused by interaction between surfaces | Frictional force | Brakes help slow a moving bicycle. |
| Example of a non-contact force | Electrostatic force | A charged comb attracts paper without initially touching it. |
| Person pushing a box | Muscular force | A person pushes a box across the floor. |
| Force exerted by a supporting surface | Normal reaction force | A chair supports a person sitting on it. |
| Force between a moving vehicle and road | Frictional force | Tyres grip the road during a turn. |
| Force that is not a contact force | Electrostatic force | A charged balloon attracts bits of paper. |
| Force acting without physical contact | Electrostatic force | A charged object attracts an oppositely charged object from a distance. |
Contact Forces vs Non-Contact Forces
| Type of Force | Meaning | Examples |
|---|---|---|
| Frictional force | Opposes relative motion or the tendency to move between contacting surfaces | Walking, bicycle brakes |
| Muscular force | Force produced by the muscles of humans or animals | Lifting a bag, pushing a box |
| Normal reaction force | Support force exerted by a surface, perpendicular to it | A table supporting a book |
| Tension force | Force transmitted through a stretched string, rope or cable | Pulling a bucket with a rope |
| Gravitational force | Force of attraction between objects that have mass | An object falling towards Earth |
| Magnetic force | Force of attraction or repulsion associated with magnets and magnetic materials | A magnet attracting an iron nail |
| Electrostatic force | Force of attraction or repulsion between electrically charged bodies | A rubbed comb attracting paper pieces |
Exam tip: Frictional, muscular, normal reaction and tension forces are contact forces. Gravitational, magnetic and electrostatic forces are non-contact forces.
Further Reference To Learn Contact and Non – Contact Forces
For a deeper understanding of contact and non-contact forces, refer to the NCERT Science textbook link given below. This additional resource will help you explore important Physics concepts related to force and strengthen your preparation for the TNPSC Physics Force Test and TNPSC General Science examination.
NCERT : (Class 12) Chapter 8 – Force and Pressure
