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How Forces Affect Motion

Chapter 6. How Forces Affect Motion

This chapter explains how forces affect the motion of objects. It introduces the concept of force, balanced and unbalanced forces, friction, and Newton's laws of motion. Students learn how force changes the state of motion of an object and how these principles explain many everyday events such as walking, riding a bicycle, catching a cricket ball and using airbags in vehicles.

Chapter Review

• Force – A force can start or stop motion, change the speed or direction of an object, and even change its shape. 
• Force is a Vector Quantity – Every force has both magnitude and direction. A change in either changes its effect.
• SI Unit of Force – The SI unit of force is the newton (N).
• Measuring Force – The magnitude of force can be measured using a spring balance. 
• Multiple Forces – More than one force can act on an object at the same time, but the object's motion depends only on the net force. 
• Balanced Forces – Equal and opposite forces cancel each other, producing zero net force.
• Unbalanced Forces – Unequal forces produce a non-zero net force that changes the motion of an object. 
• Net Force – Forces acting in the same direction are added, while opposite forces are subtracted to obtain the resultant force. 
• Direction of Net Force – The net force always acts in the direction of the larger force.
• Force of Friction – Friction always acts opposite to the direction of motion and opposes movement. 
• Role of Friction – A moving object gradually slows down and finally stops because of friction if no external force is applied. 
• Factors Affecting Friction – The force of friction depends on the nature of the surfaces in contact. Smoother surfaces produce less friction. 
• Normal Force – A surface exerts an upward force called the normal force, which balances the weight of an object placed on it. 
• Newton's First Law of Motion – An object remains at rest or continues moving with constant velocity unless acted upon by a net force. 
• Constant Velocity – If the net force on an object is zero, its velocity remains constant.
• Inertia – Inertia is the tendency of an object to resist any change in its state of rest or uniform motion. 
• Galileo's Contribution – Galileo explained that in the absence of friction, a moving object would continue moving indefinitely. 
• Newton's Second Law of Motion – When a net force acts on an object, it accelerates in the direction of the force.
• Relationship Between Force and Acceleration – Greater force produces greater acceleration, whereas greater mass produces smaller acceleration. 
• Mathematical Formula – Force = Mass × Acceleration (F = ma). 
• One Newton – One newton is the force required to produce an acceleration of 1 m s⁻² in a body of mass 1 kg. 
• Weight of an Object – Weight is the gravitational force acting on an object and is given by F = mg. 
• Acceleration Due to Gravity – Near the Earth's surface, g ≈ 9.8 m s⁻² (approximately 10 m s⁻² for calculations). 
• Applications of Newton's Second Law – Catching a cricket ball by moving the hands backward and using airbags in vehicles reduce the force of impact by increasing the stopping time. 
• Everyday Applications of Force – Walking, pushing objects, cycling, rowing a canoe, arm wrestling, tug of war and driving vehicles all demonstrate the effects of force. 
• Important Formulae
  • F = ma
  • F = mg
  • 1 N = 1 kg m s⁻²
• CBSE Exam Booster – Focus on identifying balanced and unbalanced forces, calculating net force, applying Newton's First and Second Laws, solving numerical problems using F = ma, and explaining real-life examples involving friction and inertia.

How Forces Affect Motion

Chapter 6. How Forces Affect Motion

Force is one of the most important concepts in Physics because every change in the motion of an object is caused by a force. In our daily life, we push, pull, lift, throw, kick and stop objects using different kinds of forces. This section explains the concept of force, its characteristics, types and effects with classroom-oriented explanations. 

1. Force

A force is a push or a pull acting on an object. It changes the state of rest or motion of an object and may also change its shape or size. 

Definition

Force is a physical quantity that can change the position, speed, direction or shape of an object.

Examples

• Kicking a Football – The ball starts moving because of force.
• Striking a Cricket Ball – The bat changes the direction of the ball.
• Squeezing a Lemon – The force changes the shape of the lemon.

2. Characteristics of Force

Every force has certain important characteristics that help us describe its effect on an object. 

Main Characteristics

• Magnitude – Indicates the strength of the force.
• Direction – Shows the direction in which the force acts.
• Point of Application – The position where the force is applied.
• Nature – Force may be a push or a pull.

3. Force is a Vector Quantity

Force has both magnitude and direction. Therefore, it is called a vector quantity. If either the magnitude or direction changes, the effect of the force also changes. 

Key Points

• Both magnitude and direction are necessary to describe a force.
• Two forces having the same magnitude but different directions produce different effects.
• The direction of force is represented by an arrow.

4. SI Unit of Force

Definition

The SI unit of force is the newton (N). It is named after the scientist Sir Isaac Newton. 

Important Facts

• Unit Name → newton
• Symbol → N
• CGS Unit → dyne
• Force is measured using a spring balance.

5. Measuring Force

The magnitude of force can be measured with the help of a spring balance. A spring balance measures not only the weight of an object but also the magnitude of any applied force. 

Working Principle

• The spring stretches when a force is applied.
• Greater stretching indicates a greater force.
• The scale reading gives the magnitude of the applied force.

6. Types of Force

Forces can be classified into two main categories depending on whether physical contact between objects is necessary.

Classification of Force

• Contact Forces – Require physical contact between objects.
• Non-contact Forces – Act without physical contact.

7. Contact Forces

Definition

Contact forces are forces that act only when two objects touch each other.

Examples

• Muscular Force
• Frictional Force
• Normal Force
• Tension Force

8. Non-contact Forces

Definition

Non-contact forces act even when the objects are not in physical contact.

Examples

• Gravitational Force
• Magnetic Force
• Electrostatic Force

9. Effects of Force

Depending on the situation, a force may produce one or more effects on an object. 

Effects of Force

• Starts Motion – A stationary object begins to move.
• Stops Motion – A moving object can be brought to rest.
• Changes Speed – Speed may increase or decrease.
• Changes Direction – The object may move in a different direction.
• Changes Shape – Objects like rubber balls or lemons change shape.

10. ATP Education Classroom Summary

• Force → A push or pull acting on an object.
• Force is a Vector → It has both magnitude and direction.
• SI Unit → Newton (N).
• Measuring Instrument → Spring Balance.
• Contact Forces → Muscular, Frictional, Normal and Tension Forces.
• Non-contact Forces → Gravitational, Magnetic and Electrostatic Forces.
• Main Effects → Start motion, stop motion, change speed, change direction and change shape.

ATP Education Exam Booster

Remember that every force has both magnitude and direction, making it a vector quantity. Learn the SI unit of force, the spring balance as the measuring instrument, and the difference between contact and non-contact forces. These concepts form the foundation for understanding balanced forces and Newton's laws in the next sections.

How Forces Affect Motion

Chapter 6. How Forces Affect Motion

In everyday life, more than one force often acts on an object at the same time. Whether the object moves or remains at rest depends on the combined effect of all the forces acting on it. This section explains balanced forces, unbalanced forces, net force and the addition of forces with classroom-oriented examples. 

11. Multiple Forces Acting on an Object

An object may experience two or more forces simultaneously. The final effect depends on the magnitude and direction of all the forces acting together. 

Key Points

• Single Force – Only one force acts on the object.
• Multiple Forces – Two or more forces act at the same time.
• Result Depends on Net Force – The object's motion depends on the combined effect of all forces.

12. Net Force (Resultant Force)

The single force that produces the same effect as all the forces acting together is called the net force or resultant force. 

Definition

Net force is the overall force acting on an object after combining all the individual forces.

Rules for Finding Net Force

• Same Direction – Add all the forces.
• Opposite Directions – Subtract the smaller force from the larger force.
• Direction – The net force acts in the direction of the larger force.

Example

• 10 N east + 5 N east = 15 N east.
• 20 N east and 8 N west = 12 N east.

13. Balanced Forces

When equal forces act on an object in opposite directions, they cancel each other. The net force becomes zero, so there is no change in the state of motion. 

Definition

Balanced forces are equal and opposite forces whose resultant is zero.

Characteristics

• Net Force is Zero
• No Change in Motion
• Object Remains at Rest or Continues Moving with Constant Velocity

Examples

• A book resting on a table.
• A tug of war where both teams pull with equal force.
• A person standing still on the ground.

14. Unbalanced Forces

When the forces acting on an object are unequal, the net force is not zero. The object accelerates in the direction of the net force. 

Definition

Unbalanced forces are unequal forces whose resultant is non-zero.

Characteristics

• Net Force is Non-zero
• Changes the State of Motion
• Produces Acceleration

Examples

• Kicking a stationary football.
• Pushing a shopping trolley.
• A car accelerating on a road.

15. Difference Between Balanced and Unbalanced Forces

Balanced Forces	Unbalanced Forces
Net force is zero.	Net force is not zero.
No change in the state of motion.	Changes the state of motion.
Do not produce acceleration.	Produce acceleration.
Equal and opposite forces.	Unequal forces.

16. Addition of Forces

The effect of multiple forces can be determined by adding or subtracting them according to their directions.

Cases

• Forces in the Same Direction – Add the magnitudes.
• Forces in Opposite Directions – Subtract the smaller force from the larger one.
• Resultant Direction – Always along the larger force.

17. Everyday Examples of Balanced and Unbalanced Forces

Situation	Type of Force
Book lying on a table	Balanced Forces
Person standing on the ground	Balanced Forces
Football kicked by a player	Unbalanced Forces
Car speeding up	Unbalanced Forces
Object slowing down due to a greater opposing force	Unbalanced Forces

18. ATP Education Concept Builder

• Balanced Forces → Net Force = 0.
• Unbalanced Forces → Net Force ≠ 0.
• Net Force → Combined effect of all forces.
• Same Direction → Add the forces.
• Opposite Direction → Subtract the forces.
• Motion Changes → Only when the net force is non-zero.

ATP Education Exam Booster

Remember the golden rule: Balanced forces do not change the state of motion because the net force is zero, whereas unbalanced forces always change the motion of an object because the net force is non-zero. Most CBSE competency-based questions ask students to identify whether the forces acting in a given situation are balanced or unbalanced and to calculate the net force.

How Forces Affect Motion

Chapter 6. How Forces Affect Motion

This section explains Newton's laws of motion, inertia, the relationship between force, mass and acceleration, and the concept of weight. These principles help us understand why objects start moving, stop moving and change their speed in everyday life.

19. Newton's First Law of Motion

Newton's First Law states that an object remains at rest or continues to move with uniform velocity in a straight line unless acted upon by an unbalanced external force.

Definition

An object does not change its state of rest or uniform motion unless a net external force acts on it.

Key Points

• Objects at Rest – Remain at rest until pushed or pulled.
• Moving Objects – Continue moving with constant velocity if no unbalanced force acts.
• Balanced Forces – Do not change the state of motion.
• Unbalanced Forces – Change the state of motion.

Examples

• A book remains on a table until someone pushes it.
• A football remains stationary until it is kicked.
• A moving bicycle slows down because friction acts as an external force.

20. Inertia

Every object has a natural tendency to resist any change in its state of rest or motion. This property is known as inertia.

Definition

Inertia is the property of a body by which it resists any change in its state of rest or uniform motion.

Factors Affecting Inertia

• Mass – Greater the mass, greater the inertia.
• State of Motion – Inertia acts whether the object is at rest or moving.

21. Types of Inertia

Inertia of Rest

The tendency of an object at rest to remain at rest.

Example

• Passengers move backward when a bus starts suddenly.

Inertia of Motion

The tendency of a moving object to continue moving.

Example

• Passengers move forward when a moving bus stops suddenly.

Inertia of Direction

The tendency of an object to resist a change in its direction of motion.

Example

• Passengers are pushed sideways when a vehicle takes a sharp turn.

22. Newton's Second Law of Motion

Newton's Second Law explains how force, mass and acceleration are related.

Definition

The acceleration produced in an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Important Relationships

• Greater Force → Greater acceleration.
• Greater Mass → Smaller acceleration for the same force.
• Acceleration → Always in the direction of the net force.

23. Mathematical Expression of Force

Newton's Second Law is represented mathematically by the following equation.

Formula

F = m × a

Symbol	Meaning	SI Unit
F	Force	newton (N)
m	Mass	kilogram (kg)
a	Acceleration	m/s²

24. One Newton

Definition

One newton is the force required to produce an acceleration of 1 m/s² in an object of mass 1 kg.

Formula

1 N = 1 kg × 1 m/s²

25. Weight of an Object

Weight is the gravitational force exerted by the Earth on an object.

Formula

Weight (W) = m × g

Where

• m → Mass of the object (kg)
• g → Acceleration due to gravity (≈ 9.8 m/s²)

26. Difference Between Mass and Weight

Mass	Weight
Amount of matter in an object.	Gravitational force acting on an object.
SI Unit: kilogram (kg)	SI Unit: newton (N)
Remains constant everywhere.	Changes with gravity.
Scalar quantity.	Vector quantity.

27. Applications of Newton's Second Law

• Airbags in Cars – Increase the time of impact and reduce the force on passengers.
• Catching a Cricket Ball – Moving the hands backward reduces the impact force.
• Seat Belts – Protect passengers during sudden stops.
• Sports Equipment – Helmets and pads reduce the force of impact.

Newton's Third Law of Motion

Newton's Third Law of Motion states that whenever one object exerts a force on another object, the second object simultaneously exerts an equal force in the opposite direction on the first object. These two forces are called an action–reaction pair.

Definition

For every action, there is an equal and opposite reaction.

Characteristics of Newton's Third Law

• Equal Magnitude – The action and reaction forces are always equal in magnitude.
• Opposite Direction – The two forces always act in opposite directions.
• Act on Different Objects – Action and reaction never act on the same object.
• Simultaneous Forces – Both forces occur at the same instant.

Examples

• Walking – We push the ground backward, and the ground pushes us forward.
• Swimming – A swimmer pushes water backward, and the water pushes the swimmer forward.
• Rocket Launch – Hot gases are expelled downward, and the rocket moves upward.
• Jumping from a Boat – The person moves forward while the boat moves backward.

Momentum

Momentum is the quantity of motion possessed by a moving object. It depends on both the mass of the object and its velocity. An object with greater mass or higher velocity has greater momentum.

Definition

Momentum is the product of the mass of an object and its velocity.

Formula

Momentum (p) = Mass (m) × Velocity (v)

SI Unit

The SI unit of momentum is kilogram metre per second (kg·m/s).

Factors Affecting Momentum

• Mass – Greater the mass, greater the momentum.
• Velocity – Greater the velocity, greater the momentum.

Characteristics of Momentum

• Vector Quantity – Momentum has both magnitude and direction.
• Depends on Motion – A body at rest has zero momentum.
• Direction – Momentum acts in the same direction as velocity.

Examples

• Fast Cricket Ball – A fast-moving cricket ball has greater momentum than a slowly moving ball.
• Running Athlete – An athlete gains more momentum by increasing speed.
• Moving Truck – A loaded truck has greater momentum than a motorcycle moving at the same speed because its mass is larger.
• Running Football Player – A player running at high speed has greater momentum than when walking.

Applications of Momentum

• Road Safety – Heavy vehicles possess greater momentum and require a longer distance to stop.
• Sports – Momentum helps explain batting, bowling and kicking actions.
• Transportation – Engineers consider momentum while designing braking systems.
• Rocket Science – The motion of rockets is closely related to the concept of momentum.

​Relationship Between Momentum and Force

A greater force changes the momentum of an object more rapidly. Therefore, force is directly related to the change in momentum.

ATP Education Tip

Remember these key concepts: Newton's Third Law explains action and reaction forces, while momentum explains the quantity of motion of an object. Both concepts help explain real-life situations such as walking, swimming, rocket launches, collisions and sports.

28. ATP Education Concept Builder

• Newton's First Law → Explains inertia.
• Inertia → Resistance to change in the state of motion.
• Greater Mass → Greater inertia.
• Newton's Second Law → F = ma.
• Force → Directly proportional to acceleration.
• Weight → W = mg.
• Mass → Constant everywhere.
• Weight → Depends on gravity.

ATP Education Exam Booster

Remember these four important concepts for CBSE examinations: Newton's First Law explains inertia, Newton's Second Law gives the relationship F = ma, one newton is the SI unit of force, and weight is calculated using W = mg. Questions based on inertia, mass versus weight, and force calculations are frequently asked in objective, competency-based and numerical sections.

How Forces Affect Motion

Chapter 6. How Forces Affect Motion

Friction is one of the most common contact forces that we experience every day. It plays an important role in walking, writing, driving vehicles and using machines. Although friction opposes motion, it is both useful and harmful depending on the situation. This section explains friction and its applications with classroom-oriented examples.

29. Friction

Whenever two surfaces are in contact, a force acts between them that opposes their relative motion. This opposing force is called friction.

Definition

Friction is a contact force that opposes the relative motion or the tendency of motion between two surfaces in contact.

Characteristics of Friction

• Contact Force – Friction acts only when two surfaces are in contact.
• Opposes Motion – It always acts opposite to the direction of motion.
• Acts on Both Surfaces – Equal frictional forces act on both objects.
• Produces Heat – Some mechanical energy is converted into heat.

30. Types of Friction

Depending on the condition of motion, friction is classified into different types.

Classification

• Static Friction – Acts on an object at rest and prevents it from moving.
• Sliding Friction – Acts when one surface slides over another.
• Rolling Friction – Acts when an object rolls over a surface.
• Fluid Friction (Drag) – Acts when an object moves through air or water.

31. Factors Affecting Friction

The amount of friction depends on the nature of the surfaces and the force pressing them together.

Main Factors

• Nature of Surfaces – Rough surfaces produce more friction than smooth surfaces.
• Force Between Surfaces – Greater pressure between surfaces increases friction.
• Type of Motion – Rolling friction is usually less than sliding friction.

32. Advantages of Friction

Without friction, many daily activities would become impossible.

Applications

• Walking – Friction between our feet and the ground prevents slipping.
• Writing – Friction allows a pen or pencil to write on paper.
• Driving Vehicles – Tyres grip the road because of friction.
• Braking – Friction helps stop moving vehicles safely.
• Holding Objects – Friction allows us to grip and hold objects firmly.

33. Disadvantages of Friction

• Wear and Tear – Machine parts gradually wear out.
• Heat Generation – Mechanical energy is lost as heat.
• Energy Loss – More fuel or energy is required to overcome friction.
• Reduced Efficiency – Machines become less efficient over time.

34. Methods to Reduce Friction

Method	Purpose
Lubrication	Reduces friction between moving parts.
Ball Bearings	Convert sliding friction into rolling friction.
Polishing	Makes surfaces smoother.
Streamlined Shape	Reduces air and water resistance.

35. Methods to Increase Friction

Method	Example
Making Surfaces Rough	Tread patterns on tyres.
Using Spikes	Sports shoes and mountain climbing shoes.
Applying Sand	Sand spread on slippery roads.
Grooved Brake Pads	Improve braking efficiency.

36. Applications of Force

Force is used in almost every activity of our daily life.

Examples

• Opening or Closing Doors
• Pushing Shopping Trolleys
• Playing Football or Cricket
• Lifting Heavy Objects
• Operating Machines
• Launching Rockets

37. Applications of Newton's Laws

• Seat Belts – Prevent passengers from moving forward suddenly due to inertia.
• Airbags – Increase the time of impact and reduce the force acting on passengers.
• Catching a Cricket Ball – Players move their hands backward to reduce the impact force.
• Heavy Vehicles – Require greater force to accelerate because they have greater mass.
• Rocket Launch – A large force is required to overcome Earth's gravitational pull.

38. ATP Education Classroom Concept Builder

Concept	Key Idea
Force	Push or pull.
Balanced Force	Net Force = 0.
Unbalanced Force	Changes motion.
Friction	Opposes motion.
Newton's First Law	Law of Inertia.
Newton's Second Law	Force is proportional to acceleration.
Weight	Gravitational force acting on a body.

39. Classroom Thinking Questions

• Why is it difficult to walk on a wet floor?
• Why do vehicle tyres have deep grooves?
• Why are ball bearings used in machines?
• Why do athletes wear spiked shoes?
• Why do brakes become hot after continuous use?
• Why is oil applied to bicycle chains?

ATP Education Exam Booster

For CBSE examinations, always identify which force is acting, whether friction is useful or harmful, and how Newton's laws explain the given situation. Questions based on friction, seat belts, airbags, ball bearings, tyre treads and real-life applications are frequently asked in competency-based and case-study assessments.

How Forces Affect Motion

Chapter 6. How Forces Affect Motion

This assignment is based on the complete chapter and follows the latest CBSE competency-based assessment pattern. It includes objective, descriptive, application-based, case-study and HOTS questions to strengthen conceptual understanding of force, friction, Newton's laws of motion and momentum.

Chapter Assignment

1. One Word Answer

1. A push or pull acting on an object.
2. The SI unit of force.
3. The instrument used to measure force.
4. The combined effect of all forces acting on an object.
5. Equal and opposite forces with zero resultant.
6. The property by which an object resists a change in its state of motion.
7. The force that opposes motion between two surfaces.
8. The product of mass and velocity.
9. The gravitational force acting on an object.
10. The law stated as "For every action, there is an equal and opposite reaction."

2. Fill in the Blanks

1. Force is a __________ quantity because it has magnitude and direction.
2. The SI unit of force is __________.
3. Balanced forces have __________ net force.
4. Unbalanced forces produce __________.
5. Force is measured using a __________.
6. The formula for force is __________.
7. The formula for momentum is __________.
8. Weight is calculated using the formula __________.
9. Friction always acts __________ the direction of motion.
10. Action and reaction act on __________ objects.

3. True or False

1. Force can change the shape of an object.
2. Balanced forces always change the motion of an object.
3. Momentum depends on both mass and velocity.
4. Mass and weight are the same physical quantities.
5. Friction is always harmful.
6. Newton's First Law is also called the Law of Inertia.
7. Action and reaction act on the same object.
8. A body at rest has zero momentum.
9. Weight changes with gravity.
10. Rolling friction is generally less than sliding friction.

4. Match the Following

Column A	Column B
Force	Push or Pull
Balanced Forces	Net Force = 0
Unbalanced Forces	Produce Acceleration
Inertia	Resistance to Change
Newton's First Law	Law of Inertia
Newton's Second Law	F = ma
Momentum	p = mv
Weight	W = mg
Friction	Opposes Motion
Newton's Third Law	Action and Reaction

5. Very Short Answer Questions

1. Define force.
2. Why is force called a vector quantity?
3. State the SI unit of force.
4. What is a balanced force?
5. What is an unbalanced force?
6. Define inertia.
7. Write Newton's First Law of Motion.
8. State Newton's Second Law of Motion.
9. Define momentum.
10. State Newton's Third Law of Motion.

6. Short Answer Questions

1. Explain the characteristics of force.
2. Differentiate between balanced and unbalanced forces.
3. Describe the different effects of force with examples.
4. Explain the concept of inertia with suitable examples.
5. Differentiate between mass and weight.
6. Describe the advantages and disadvantages of friction.
7. Explain different methods of reducing friction.
8. State and explain Newton's Second Law with the formula F = ma.
9. Explain momentum and the factors affecting it.
10. Explain Newton's Third Law with two everyday examples.

7. Long Answer Questions

1. Explain Newton's First, Second and Third Laws of Motion with suitable examples.
2. Describe the concept of force and its effects on the motion of an object.
3. Explain balanced and unbalanced forces with real-life applications.
4. Discuss friction, its advantages, disadvantages and methods of reducing it.
5. Explain momentum, its formula, SI unit and practical applications.
6. Differentiate between mass, weight and momentum.
7. Discuss the applications of Newton's laws in everyday life.
8. Explain why force is considered a vector quantity.
9. Describe how force and momentum are related.
10. Explain the importance of friction in transportation and sports.

8. Case Study Questions

Case Study – 1

A football lying on the ground is kicked by a player and starts moving towards the goal.

1. Which force starts the motion of the football?
2. Are the forces balanced or unbalanced?
3. Which law explains the change in motion?
4. What happens to the momentum of the ball after it is kicked?

Case Study – 2

A passenger standing inside a bus moves backward when the bus starts suddenly.

1. Name the property responsible for this effect.
2. Which law of motion explains this situation?
3. What type of inertia is observed?
4. How can this effect be reduced?

Case Study – 3

A cricket player pulls his hands backward while catching a fast-moving ball.

1. Which law of motion explains this action?
2. Why does the player move the hands backward?
3. How does this reduce the force of impact?
4. How is momentum involved in this situation?

Case Study – 4

A loaded truck and a motorcycle are moving with the same speed on a highway.

1. Which vehicle has greater momentum?
2. Why?
3. Which vehicle requires more force to stop?
4. State the formula for momentum.

Case Study – 5

A swimmer pushes water backward with his hands and moves forward.

1. Which law of motion explains this?
2. Identify the action force.
3. Identify the reaction force.
4. Give one more example based on the same law.

9. Competency-Based Questions

1. Why is force required to change the motion of an object?
2. How can balanced forces keep an object moving with constant velocity?
3. Why do heavy vehicles require a greater braking distance?
4. How does friction help us walk safely?
5. Why are tyre treads made rough?
6. How does lubrication improve the efficiency of machines?
7. Why does a loaded truck have greater momentum than a motorcycle moving at the same speed?
8. Explain why airbags reduce injuries during accidents.
9. Why do action and reaction never cancel each other?
10. How are Newton's laws useful in sports and transportation?

10. HOTS Questions

1. A bus and a bicycle are moving with the same speed. Which one has greater momentum? Justify your answer.
2. Why does a person slip more easily on a wet floor than on a dry floor?
3. Explain why a rocket can move upward even though there is no air in space.
4. Why does a cricketer move his hands backward while catching a fast ball?
5. Can an object move with zero net force? Explain with an example.
6. Why do action and reaction forces never balance each other?
7. How would life be affected if there were no friction on Earth?
8. A body has a large mass but is at rest. Does it have momentum? Give reasons.
9. Why is force considered a vector quantity while mass is a scalar quantity?
10. How do Newton's laws help engineers design safer vehicles?