Basic concepts of laws of motion

(1) Newton's first law of motion:-

'A body continues to be in state of rest or uniform motion unless it is acted upon by some external force to act otherwise'

(2) Newton's second law of motion:-

'Rate of change of momentum of a body is proportional to the applied force and takes place in the direction of action of force applied'

Mathematically,

=m

where,

SI unit of force is Newton (N).

(3) Impulse is the product of force and time which is equal to the change in momentum

Impulse=

=Δ

(4) Newton's third law of motion:-

'To every action there is always an equal and opposite reaction'

(5) According to the law of conservation of linear momentum

Initial momentum = final momentum

m

For equilibrium of a body

1. An accelerated frame is called non interial frame while am non accelerated frame is called interial frame

2. Newton Ist law are valid in intertial frame only

3 Apparent weight of a body in the lift

Going Upward with acceleration a

W=m(g+a)

Going Down with acceleration a

W=m(g-a)

4.Always draw free body diagram to solve the force related problems

(1) Newton's first law of motion:-

'A body continues to be in state of rest or uniform motion unless it is acted upon by some external force to act otherwise'

(2) Newton's second law of motion:-

'Rate of change of momentum of a body is proportional to the applied force and takes place in the direction of action of force applied'

Mathematically,

**F**=d**p**/dt=m

**a**where,

**F**=external force applied**p**=m**v**,momentum of the body**a**=accelerationSI unit of force is Newton (N).

(3) Impulse is the product of force and time which is equal to the change in momentum

Impulse=

**F**Δt=Δ

**p**(4) Newton's third law of motion:-

'To every action there is always an equal and opposite reaction'

**F**_{AB}=-**F**_{BA}(5) According to the law of conservation of linear momentum

Initial momentum = final momentum

m

_{1}**v**1+m_{2}**v**2=m_{1}**v**1^{'}+m_{2}**v**2^{'}For equilibrium of a body

**F**_{1}+**F**_{2}+**F**_{3}=0**Some points to note**1. An accelerated frame is called non interial frame while am non accelerated frame is called interial frame

2. Newton Ist law are valid in intertial frame only

3 Apparent weight of a body in the lift

Going Upward with acceleration a

W=m(g+a)

Going Down with acceleration a

W=m(g-a)

4.Always draw free body diagram to solve the force related problems

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