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Newton's Laws Of Motion - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main

Quick Facts

  • Newton’s Second and Third Law of motion is considered one the most difficult concept.

  • 43 Questions around this concept.

Solve by difficulty

A machine gun fires a bullet of mass of 40g with a velocity of 1200 ms-1 The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most?

When forces F1,F2 , and F3 are acting on a particle of mass  m such that F2 and F are mutually perpendicular, then the particle remains stationary If the force F1 is now removed then the acceleration of the particle is :

A mass of 10 kg is there; How much force is required to push the block 100 m in a straight direction in a time interval of 10 secs? \left ( g=10ms^{-2} \right )

Concepts Covered - 1

Newton’s Second and Third Law of motion
  1. Newton’s second law of motion:-

  • It states that the acceleration of the particle measured from an inertial frame is given by the (vector) sum of all the forces acting on the particle divided by its mass (only when mass is constant), i.e.,

                          \vec{a}=\frac{\vec{F}}{m}\Rightarrow \vec{F}=m\vec{a}

  • Impulse:

  1.  The quantity   \vec{I}=\int_{t_{1}}^{t_{2}}\vec{F}\cdot dtis known as the impulse of the force F during the time interval t1 to t2 and

Is equal to the change in the momentum of the body on which it acts,

i.e. P_f-P_1=\int_{P_1}^{P_1}dP=\int \frac{dP}{dt}*dt=\int Fdt⇒ Area under force and time graph is an impulse.

                                

             2.    Dimension- MLT-1

            3.    Unit- kg-m/sec

  • Impulse Momentum Theorem- Newton’s 2nd law can also be written as:

                      Rate of change in momentum = Force Applied

                           \vec{F}=\frac{d\vec{p}}{dt}

    Inertial mass:

  • This is defined by Newton's 2nd law-  F = ma, which states that when a force F is applied to an object, it will accelerate proportionally, and that constant of proportion is the mass of that object.
  • To determine the inertial mass, you apply a force of F Newtons to an object, measure the acceleration in m/s2                                                        Inertial \ mass (kg)= \frac{F}{a}

    2.    Newton’s third law of motion:-

  • It states that "If a body A exerts a force F on another body B, then B exerts a force (-F) on A." 

  • Action and reaction never act on the same body.

    3. Law of Conservation of Linear Momentum:

  • As we know, \vec{F}=\frac{d\vec{p}}{dt}, If the net external force acting on the system is zero then the change in momentum of system=0

  • \Rightarrow \Delta p=0

     \therefore p_{system}=p_1+p_2+p_3+......=constant

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Newton’s Second and Third Law of motion

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