EASY
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What is meant by impulse of force?

Important Questions on Laws of Motion

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A machine gun fires a bullet of mass 40 gram at a speed of 1200 m s-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?
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A force ‘F’ is applied on one end of a rope of length ‘a’. P and Q are two points of length ‘b’ from nearest end. The ratio of tensions in string at P & Q is :

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EASY
An object of mass 10 gm is moving with an acceleration of 10 m/s2. Force acting on the object will be:
MEDIUM
A diwali rocket is ejecting 0.05kg of gases per second at a velocity of 400 m s-1. The accelerating force on the rocket is
HARD

A particle of mass 0.3 kg is subjected to a force F = Kx with K = 15 N/m, what will be its acceleration if it is released from a point x = 20 cm.

MEDIUM

The velocity-time graph of a ball of mass 20 g moving along a straight line on a long table is given in figure.The force exerted by the table on the ball to bring it to rest is :

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EASY

The variation in momentum with time, for a body under collision is shown in figure. The maximum & minimum instantaneous forces are respectively on these points:

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EASY

Read the following statements and choose the correct option:
Statement: Newton's second law of motion gives the measurement of force. 
Reason: According to Newton's second law of motion, force is directly proportional to the rate of change of momentum. 

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A small block of material having relative density 13 is immersed in a liquid and released. The block starts moving upwards with an acceleration a. The value of a is :(g is the acceleration due to gravity)
MEDIUM

A dynamometer D is attached to two masses m1=3 kg and m2=5 kg. Forces of f1=9 N and f2=25 N are applied to the masses as shown.

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The dynamometer will read :

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Two similar trucks are moving with the same velocity on a road. One of them is loaded while the other is empty. Which of the two will require a larger force to stop it?

EASY

In a two body collision, the momentum is varying with time as shown in graph. The instantaneous force is maximum at: 

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MEDIUM
Figure shows the velocity versus time graph for a block of mass 50 g sliding on a rough floor. The average rate at which energy dissipates (in Js-1) due to the force of friction is:  
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MEDIUM
A particle having a mass 0.5 kg is projected under gravity with a speed of 98 m sec-1 at an angle of 60°.  The magnitude of the change in momentum (in N sec) of the particle after 10 seconds is g=9.8 m s-2
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Mathematical formulation of second law of motion is given as:
EASY
When a striker hits the bottom of the pile of coins placed at the centre of a _____, only the lowest coin is removed.
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Calculate the force needed to speed up a car with a rate of 9 ms-2 , if the mass of the car is 950 kg .
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The physical quantity which is equal to the rate of change of momentum is
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When external force acting on a body is _____, the linear momentum of body is constant.