Class 10 Laws of Motion Explanation, Examples & Applications and Question Practice

Overview of Class 10 Laws of motion

The Class 10 Laws of Motion, formulated by Sir Isaac Newton, are the fundamental principles that describe the relationship between the motion of an object and the forces acting on it. These laws play a crucial role in understanding various physical phenomena, from everyday activities to complex scientific applications like space travel and engineering.

In this detailed article, we will discuss Newton’s Three Laws of Motion along with real-life examples, mathematical explanations, and applications.

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What are Newton’s Laws of Motion?

Class 10 Laws of Motion are three fundamental laws that explain how objects behave when forces act upon them. These laws include:

1. 1. Newton’s First Law of Motion (Law of Inertia)

1. 1. Newton’s Second Law of Motion (Law of Acceleration)

1. 1. Newton’s Third Law of Motion (Law of Action and Reaction)

Newton’s First Law of Motion (Law of Inertia)

Statement:

“An object at rest remains at rest, and an object in motion continues in motion with the same speed and in the same direction unless acted upon by an external force.”

Explanation:

This law is also called the Law of Inertia, where inertia is the tendency of an object to resist changes in its state of motion. If no force is applied to an object, it will either remain at rest or move in a straight line with constant velocity.

Mathematical Representation:

• • Inertia depends on mass: Heavier objects have more inertia and require more force to change their state of motion.

Examples of Newton’s First Law:

1. 1. A Book on a Table: A book lying on a table remains there unless an external force (like a push) moves it.

1. 1. Passenger in a Moving Car: When a car suddenly stops, passengers lurch forward due to inertia. Similarly, when a car accelerates suddenly, passengers feel a push backward.

1. 1. Rolling Ball on the Ground: A ball rolling on the ground eventually stops due to friction acting as an external force. Class 10 Laws of Motion

Image Representation

Newton’s Second Law of Motion (Law of Acceleration)

Statement:

“The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The direction of acceleration is in the direction of the applied force.” Class 10 Laws of Motion

Mathematical Formula:

                                    F=ma 

Where:

• • F = Force (in Newtons)

• • m = Mass of the object (in kg)

• • a = Acceleration (in m/s^2)

This means that if more force is applied to an object, it accelerates faster. However, if the object is heavy (has a larger mass), it requires more force to accelerate. Class 10 Laws of Motion

Examples of Newton’s Second Law:

1. 1. Pushing a Shopping Cart: An empty cart accelerates faster when pushed than a heavily loaded cart.

1. 1. Kicking a Football: A stronger kick applies more force, resulting in greater acceleration and speed of the ball.

1. 1. Cycling: The harder you pedal, the greater the acceleration of the bicycle.

Numerical Example:

Problem: If a force of 20 N is applied to a 5 kg object, what is its acceleration?

Solution:
Using F=ma = ma,

20=5×a

20=5×a

a=20/5=4 m/s^2

Thus, the object accelerates at 4 m/s².

Image Representation

Newton’s Third Law of Motion (Law of Action and Reaction)

Statement:

“For every action, there is an equal and opposite reaction.” Class 10 Laws of Motion

Explanation:

Whenever a force is applied to an object, the object applies an equal force in the opposite direction. Forces always come in action-reaction pairs, which means that no force exists alone.

Examples of Newton’s Third Law:

1. 1. Walking on the Ground: When you walk, you push the ground backward, and the ground pushes you forward with equal force.

1. 1. Jumping off a Boat: When you jump from a boat onto the shore, the boat moves backward due to the reaction force.

1. 1. Rocket Launching: A rocket expels hot gases downward, and the reaction force pushes it upward.

Image Representation

Applications of Newton’s Laws of Motion

1. 1. Automobiles: Newton’s laws explain braking, acceleration, and seatbelt mechanisms in cars.

1. 1. Sports: Understanding force and motion helps in games like football, cricket, and basketball.

1. 1. Aerospace Engineering: Rockets and airplanes function based on these laws.

1. 1. Construction and Engineering: Bridges and buildings are designed keeping motion laws in mind.

1. 1. Everyday Life: Walking, running, cycling, and using tools all involve these laws.

Important Concepts Related to Laws of Motion

1. Inertia and Types of Inertia

• • Inertia of Rest: A body remains at rest unless an external force moves it.

• • Inertia of Motion: A moving object continues moving unless a force stops it. Class 10 Laws of Motion

• • Inertia of Direction: A moving object continues in the same direction unless a force changes its path.

2. Momentum and its Conservation

Momentum (pp) is given by:

               p=mv 

where m is mass and v is velocity.

Law of Conservation of Momentum:

“In an isolated system, the total momentum remains constant unless acted upon by an external force.”

Example: When a gun is fired, the bullet moves forward, and the gun recoils backward, conserving momentum. Class 10 Laws of Motion

Question Practice Class 10 Laws of motion

1. Which of the following statements correctly describes Newton’s First Law of Motion?

(a) A body continues in its state of rest or uniform motion unless acted upon by an external force.
(b) Force is equal to mass times acceleration.
(c) For every action, there is an equal and opposite reaction.
(d) A body moves faster when a greater force is applied. Class 10 Laws of Motion

Explanation:

✅ (a) Correct Answer: Newton’s First Law states that an object remains in its state of rest or uniform motion unless an external force acts upon it. This is also called the Law of Inertia.
❌ (b) Incorrect: This statement belongs to Newton’s Second Law of Motion. Class 10 Laws of Motion
❌ (c) Incorrect: This statement describes Newton’s Third Law of Motion.
❌ (d) Incorrect: This statement is a partial description of Newton’s Second Law but not the First Law. Class 10 Laws of Motion

2. A book placed on a table remains at rest. This is due to which property?

(a) Momentum
(b) Inertia
(c) Acceleration
(d) Friction

Explanation: Class 10 Laws of Motion

❌ (a) Incorrect: Momentum refers to the quantity of motion an object has, which is not relevant here.
✅ (b) Correct Answer: The book resists changes in its state of rest due to inertia (Newton’s First Law).
❌ (c) Incorrect: Acceleration is related to Newton’s Second Law and does not apply here. Class 10 Laws of Motion
❌ (d) Incorrect: Friction opposes motion but does not explain why the book remains at rest. Class 10 Laws of Motion

3. A force of 10 N is applied to a 2 kg object. What is the acceleration?

(a) 2 m/s²
(b) 5 m/s²
(c) 10 m/s²
(d) 20 m/s²

Solution: Class 10 Laws of Motion

Solution:

$$a=F/m=10N\hspace{0.17em}/2\hspace{0.17em}kg=5\text{m/s²}$$

Answer: The acceleration is 5 m/s².

✅ (b) Correct Answer: Acceleration is 5 m/s².
❌ (a), (c), (d) Incorrect: These values are obtained from incorrect calculations. Class 10 Laws of Motion

4. When a person jumps from a boat, the boat moves backward. This is an example of:

(a) Newton’s First Law
(b) Newton’s Second Law
(c) Newton’s Third Law
(d) Conservation of Energy

Explanation: Class 10 Laws of Motion

✅ (c) Correct Answer: As the person pushes against the boat (action), the boat moves in the opposite direction (reaction), following Newton’s Third Law.
❌ (a), (b), (d) Incorrect: These laws do not explain this phenomenon. Class 10 Laws of Motion

5. A 50 kg object experiences an acceleration of 2 m/s². What is the force acting on it?

(a) 25 N
(b) 50 N
(c) 75 N
(d) 100 N

Solution: Class 10 Laws of Motion

Solution:

$$F=m\cdot a=50\hspace{0.17em}kg\cdot 2\hspace{0.17em}m/s²=100\hspace{0.17em}N$$

Answer: The force acting on the object is 100 N.

✅ (d) Correct Answer: Force is 100 N. Class 10 Laws of Motion
❌ (a), (b), (c) Incorrect: These values result from incorrect calculations. Class 10 Laws of Motion Class 10 Laws of Motion

6. Which quantity remains constant in the absence of external forces?

(a) Velocity
(b) Acceleration
(c) Momentum
(d) Force

Explanation: Class 10 Laws of Motion

✅ (c) Correct Answer: According to the Law of Conservation of Momentum, in an isolated system, momentum remains constant.
❌ (a), (b), (d) Incorrect: Velocity and acceleration can change, and force is not constant without external influence. Class 10 Laws of Motion

7. A car stops suddenly. Passengers move forward due to:

(a) Friction
(b) Gravity
(c) Inertia
(d) Force

Explanation: Class 10 Laws of Motion

✅ (c) Correct Answer: Passengers move forward due to inertia, resisting the sudden stop (Newton’s First Law).
❌ (a), (b), (d) Incorrect: Friction and gravity do not cause this effect. Class 10 Laws of Motion

8. A gun recoils when fired due to:

(a) Gravity
(b) Newton’s Third Law
(c) Air Resistance
(d) Inertia

✅ (b) Correct Answer: The bullet moves forward (action), and the gun moves backward (reaction).
❌ (a), (c), (d) Incorrect: These do not explain the recoil effect. Class 10 Laws of Motion Class 10 Laws of Motion

9. A 10 kg object moving at 5 m/s has momentum of:

(a) 20 kg·m/s
(b) 50 kg·m/s
(c) 100 kg·m/s
(d) 500 kg·m/s

✅ (b) Correct Answer: 50 kg·m/s
❌ (a), (c), (d) Incorrect: Incorrect calculations. Class 10 Laws of Motion Class 10 Laws of Motion

10. A ball is dropped from a height. It falls due to:

(a) Newton’s First Law
(b) Newton’s Second Law
(c) Gravity (Force acting downward)
(d) Air resistance

✅ (c) Correct Answer: The ball falls due to gravity (a force acting downward). Class 10 Laws of Motion

11. A force of 15 N acts on a 3 kg object. Find acceleration.

(a) 5 m/s²
(b) 10 m/s²
(c) 15 m/s²
(d) 45 m/s²

✅ (a) Correct Answer: 5 m/s² Class 10 Laws of Motion

12. The SI unit of force is:

(a) Joule
(b) Watt
(c) Newton
(d) Pascal

✅ (c) Correct Answer: SI unit of force is Newton (N). Class 10 Laws of Motion

13. A moving object will continue moving unless:

(a) Friction acts
(b) Gravity stops it
(c) Air resistance stops it
(d) An external force acts

✅ (d) Correct Answer: Newton’s First Law states that motion continues unless an external force acts. Class 10 Laws of Motion Class 10 Laws of Motion

14. Which has more inertia?

(a) A bicycle
(b) A ball
(c) A book
(d) A truck

✅ (d) Correct Answer: A truck has more mass, so it has more inertia. Class 10 Laws of Motion

15. If the action force is a bat hitting a ball, what is the reaction force?

(a) The ball hitting the bat
(b) The ball moving forward
(c) Gravity pulling the ball
(d) Air resistance on the ball

✅ (a) Correct Answer: The ball applies an equal force on the bat (Newton’s Third Law). Class 10 Laws of Motion