Question

newtons laws and its comletness in describing particle motion

Answer 1

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$\underline\bold{\huge{ANSWER \: :}}$

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1] NEWTON'S FIRST LAW OF MOTION

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➡ Every object in this universe continues in its state of rest or uniform motion in a straight line unless compelled by an external force to change that state.

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2] NEWTON'S SECOND LAW OF MOTION

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

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3] NEWTON'S THIRD LAW OF MOTION

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➡ To every action, there is an equal and opposite reaction.

[NOTE : Action and reaction forces always acts simultaneously on two different bodies.]

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4] DESCRIPTION OF PARTICLE MOTION ON THE BASIS OF ITS COMPLETENESS BY NETWON'S LAWS

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➡ Whenever a particle is acted upon by an external force, it will changes its initial state. This is the main statement which indicates the completeness of all the fundamental laws of Newton about describing the motion of a particle. We can also describe it in three ways according to the FIRST, SECOND and THIRD LAWS respectively.

(A) While giving a long jump, an athlete used to run a long distance so that the inertia of motion helps him to have a longer jump.

(B) When a glass vessel falls from a height on a hard floor, it comes to rest almost in a very short time and the floor exerts a large force on the vessel hence it breaks. But, if it falls on a carpet (or sand), the time duration in which the vessel comes to rest increases and so the carpet (or sand) exerts a less amount of force on the vessel and it doesn't break.

(C) While catching a ball, the ball exerts a force (action) on the palm of the cricketer and the cricketer also exerts an equal force (reaction) on the ball to stop it.

Here, in all the above three examples, we are getting some facts or examples which are illustrating the completeness of the motion of a body or an object. Thus, we can say that, Newton's law can illustrate the completeness in describing particle motion.

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$\bold{MORE \: \: EXAMPLES}$

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1] When a person fires a bullet from a gun, a force is exerted on the bullet (action) and the gun also experiences an equal force (reaction) as shown in the first figure.

2] When a man applies a force (action) backward by his foot on the ground against the frictional force, the ground exerts an equal and oplosite force (reaction) forward on his foot. The horizontal component of the force of reaction enables the man to move forward.

3] When a passenger jumps out of a moving train, he falls down because inside the train his whole body was in a state of motion with the train. On jumping out of the moving train, as soon as his feet touch the ground, the lower part of his body comes tonrest while the upler part still remains in motion due to the inertia of motion.

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