HP TGT Physics — Chapter 2: Laws of Motion

 HP TGT Physics — Chapter 2: Laws of Motion

Key Points with Explanation

Ø  Newton’s First Law of Motion

Also called the Law of Inertia.
Statement: An object stays at rest or keeps moving in a straight line with constant speed unless an external force acts on it.
Example: A book on a table stays at rest until pushed.

Ø  Inertia

Inertia is the tendency of an object to resist a change in its state of motion or rest.
More mass = more inertia.
Example: It is harder to push a loaded truck than an empty one.

Ø  Newton’s Second Law of Motion

It explains how force affects motion.
Statement: The rate of change of momentum of an object is directly proportional to the applied force and takes place in the direction of the force.
Formula: F = ma
(F = Force, m = mass, a = acceleration)

Ø  Momentum (p)

Momentum is the product of mass and velocity.
Formula: p = mv
Momentum is a vector quantity.
Example: A fast-moving truck has more momentum than a slow-moving bike.

Ø  Newton’s Third Law of Motion

Statement: For every action, there is an equal and opposite reaction.
Example: When you jump, your feet push the ground backward; the ground pushes you forward.

Ø  Impulse

Impulse is the product of force and time for which force acts.
Formula: Impulse = Force × Time = Change in momentum.
Example: A cricketer lowers his hands while catching a ball to reduce force.

Ø  Law of Conservation of Momentum

When no external force acts on a system, the total momentum remains constant.
Example: When a gun is fired, the forward bullet momentum is equal to the backward recoil of the gun.

Ø  Important Formulas

Ø  MCQs for Laws of Motion

1. Which law is known as the law of inertia?
A) First Law
B) Second Law
C) Third Law
D) None of these

2. What is the SI unit of force?
A) Newton
B) Joule
C) Watt
D) Pascal

3. A cricketer lowers his hands while catching a ball to:
A) Increase force
B) Decrease time
C) Reduce force of impact
D) Throw the ball far

4. Which of these shows Newton’s Third Law?
A) Walking
B) Sleeping
C) Sitting
D) Eating

5. Momentum is:
A) Scalar quantity
B) Vector quantity
C) Both
D) None

Ø  Quick Revision Tip:

👉 Remember: 1st Law — Inertia, 2nd Law — F = ma, 3rd Law — Action-Reaction.
Practice numerical questions on momentum and impulse.

Ø  Next Chapter:

👉 Next: Work, Energy & Power — Key Points + Explanation + MCQs

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