EASY
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All surfaces shown in figure are assumed to be frictionless and the pulleys and the string are light. The acceleration of the block of mass 2 kg is :

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Important Questions on Laws of Motion

EASY
The time taken by a force of 2 N to produce a change of momentum of 0.4 kg m s-1 in a
HARD
A body of mass m is moving in a straight line with momentum p. Starting at time t=0, a force F=at acts in the same direction on the moving particle during time interval of T. So that its momentum changes from p to 2p. The value of T is
MEDIUM
A steam of water flowing horizontally with a speed of 25 ms-1 gushes out of a tube of cross-section area 10-3 m2, and hits at a vertical wall nearby. What is the force exerted on the wall by the impact of water ?
MEDIUM
Two blocks of masses m1 and m2 are suspended by a massless string passing over a smooth pulley. If the acceleration of the system is g8,then the ratio of the masses m2 m1=
EASY
A machine gun has a mass 5 kg. It fires 50 gram bullets at the rate of 30 bullets per minute at a speed of 400 m s-1. What force is required to keep the gun in position?
EASY
A force of 0.03 N acts on a body of mass 0.5 kg, which is initially at rest, for a duration of 10 seconds. Then find the momentum acquired by the body.
MEDIUM
The force on a body of mass 1 kg is 20 i^+10 j^ N. If it starts from rest, then the position of the body at time t=2 s, is
EASY
A block of mass 48 kg kept on a smooth horizontal surface is pulled by a rope of length 4 m by a horizontal force of 25 N applied to the other end. If the linear density of the rope is 0.5 kg m-1, the force acting on the block is
MEDIUM
A particle moving in the xy-plane experiences a velocity dependent force F=kυyi^+υxj^, where υx and υy are the x and y components of its velocity υ. If a is the acceleration of the particle, then which of the following statements is true for the particle ?
EASY
Two bodies of mass 4 kg and 6 kg are tied to the ends of a massless string. The string passes over a pulley which is frictionless (see figure). The acceleration of the system in terms of acceleration due to gravity g is:
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EASY
A machine gun can fire 200 bullets min-1. If 35 g bullets are fired at a speed of 750 m s-1, the average force exerted by the gun on the bullets is,
HARD

The machine as shown has 2 rods of length 1 m connected by a pivot at the top. The end of one rod is connected to the floor by a stationary pivot and the end of the other rod has roller that rolls along the floor in a slot. As the roller goes back and forth, a 2 kg weight moves up and down. If the roller is moving towards right at a constant speed, the weight moves up with a :

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MEDIUM
Two horizontal forces F1 and F2 act on a ball of mass 8 kg. The forces are such that F1=14 N i^ and F2=20 N. If the x component of velocity vx changes linearly by 3 m s-1 in 1 sec, the angle between two forces is
MEDIUM
When will a body of mass 20 kg moving at 15 m s-1, subjected to a retarding force of 100 N, come to rest?
HARD
A ball of mass 0.45 kg which is initially at rest is hit by a bat. The bat remains in contact with the ball for 3×10-3 s. During this time period the force on the ball by the bat is given as Ft=α×106t-β×109t2 N where α and β are constants. The ball's speed immediately as it loses contact with the bat is 20 m s-1. The correct relation between α and β is
MEDIUM
The velocity (v) of a particle (under a force F) depends on its distance (x) from the origin (with x>0 ) v1x. Find how the magnitude of the force (F) on the particle depends on x ?
MEDIUM

Two blocks A and B of masses 1.5 kg and 0.5 kg respectively are connected by a massless inextensible string passing over a frictionless pulley as shown in the figure. Block A is lifted until block B touches the ground and then block A is released. The initial height of block A is 80 cm when block B just touches the ground. The maximum height reached by block B from the ground after the block A falls on the ground is

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MEDIUM

Calculate the acceleration of the block and trolly system shown in the figure. The coefficient of kinetic friction between the trolly and the surface is 0.05. (g=10 m s-2, mass of the string is negligible and no other friction exists).

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HARD
A ball is thrown upward with an initial velocity V0 from the surface of the earth. The motion of the ball is affected by a drag force equal to  mγv2 (where m is mass of the ball, v is its instantaneous velocity and γ is a constant). Time taken by the ball to rise to its zenith is:
MEDIUM
A stream of water flowing horizontally with a speed of 15 ms-1 gushes out of a tube of cross-sectional area 10-2 m2 and hits a vertical wall nearby. The force exerted on the wall by the impact of water (assuming it does not rebound) is