Question

DEFINE SECOND LAW OF MOTION ( CLASS 9 PHYSICS)

Answer 1

Second law of motion :-

The rate of change of momentum is directly proportional to the applied force, and takes place in the direction in which the force acts.

We can aslo write it as,

→ Force ∝ Change in momentum/Time taken

Example :

• A cricket player moves his hands backwards on catching a fast cricket ball.

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★ First Law of Motion :

A body at rest will remain at rest and a body in motion will continue in motion in a straight line with uniform speed,unless it is compelled by an external force to change its state of rest or of uniform motion.

★ Inertia :

Inertia is that property of a body due to which it resists change in its state of rest or of uniform motion.

Example :

• A cricket ball has more inertia than a rubber ball of the same size.

★ Third Law of Motion :

To every action there is an equal and opposite reaction.

Example :

• When we walk on the ground,then our foot ground backward and,in return,the ground pushes our foot forward. The forward reaction exerted by the ground on our foot makes us to walk forward.

Answer 2

Answer:

✯ Second law of motion :-

$\mapsto$ Second Law of motion states that the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force.

❖ Formula to find the second law of motion :-

$\large\purple{\underline{{\boxed{\textbf{F\: =\: ma}}}}}$

where,

• F = Force applied
• m = Mass of the body
• a = Acceleration produced

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