EASY
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A shell of mass 10 kg is moving with a velocity of 10 ms-1 when it blasts and forms two parts of mass 9 kg and 1 kg respectively. If the 1st mass is stationary, the velocity of the 2nd is

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Important Questions on Systems of Particles and Rotational Motion

EASY
Two particles which are initially at rest move towards each other under the action of their mutual attraction. If their speeds are v and 2v at any instant, then the speed of center of mass of the system is,
MEDIUM
A body of mass 4m is lying in x - y plane at rest. It suddenly explodes into three pieces. Two pieces, each of mass m move perpendicular to each other with equal speeds υ. The total kinetic energy generated due to explosion is:
MEDIUM
A wedge of mass M=4m lies on a frictionless plane. A particle of mass m approaches the wedge with speed v. There is no friction between the particle and the plane or between the particle and the wedge. The maximum height climbed by the particle on the wedge is given by:
MEDIUM
A bullet of mass m moving horizontally with speed v0 hits a wooden block of mass M that is suspended from a massless string. The bullet gets lodged into the block and comes into halt. If the block-bullet combine swings to a maximum height h then how much of the initial kinetic energy of the bullet is lost in the collision?
EASY
A block of mass kg is free to move along the X -axis. It is at rest and from time t=0 onwards it is subjected to a time-dependent force Ft in the x -direction. The force Ft varies with t as shown in figure. The kinetic energy of the block at t=4 s is

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MEDIUM
A ball of mass M moving with a speed of 2 m s-1 hits another ball of mass 1 kg moving in the same direction with a speed of 1 m s-1. If the kinetic energy of center of mass is 43 Joule, then the magnitude of M is
HARD
A man (mass =50 kg ) and his son (mass =20 kg ) are standing on a frictionless surface facing each other. The man pushes his son so that he starts moving at a speed of 0.70 m s-1 with respect to the man. The speed of the man with respect to the surface is:
EASY
Two particles of masses m1 and m2 have equal kinetic energies. The ratio of their momentum is:
EASY
A bomb at rest explodes into 3 parts of same mass. The momentum of two parts is -3pi^ and 2pj^ respectively. The magnitude of momentum of the third part is
MEDIUM
In free space, a particle A of charge 1 μC is held fixed at point P . Another particle B of the same charge and mass 4 μg is kept at a distance of 1 mm from P. If B is released, then its velocity at a distance of 9 mm from P is:
[Take  14πϵ0=9×109 N m2 C-2 ]
EASY
Two masses of 1 g and 4 g are moving with equal kinetic energy. The ratio of the magnitudes of their linear momentum is
EASY

Two particles of masses m1, m2 move with initial velocities u1 and u2. On collision, one of the particles get excited to higher level, after absorbing energy ε. If final velocities of particles be v1 and v2 then we must have:

MEDIUM
A stationary body explodes into two parts of masses M1 and M2. They move in opposite directions with velocities v1 and v2. The ratio of their kinetic energies is
MEDIUM
The escape velocity from the surface of earth is ve. A body is projected with velocity 3ve. With what constant velocity will it move in the inter planetary space?
EASY
Two bodies of mass m and 4m have equal kinetic energy. What is the ratio of their momentum?
EASY
An object of mass m1 collides with another object of mass m2, which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses m2:m1 is :
EASY
If momentum is decreased by 20%, kinetic energy will decrease by
MEDIUM
A ball is thrown vertically up (taken as +z-axis ) from the ground. The correct momentum-height (p-h) diagram is:
MEDIUM
A bullet of mass 10 g moving horizontally with a velocity of 400 s-1 strikes a wooden block of mass 2 kg which is suspended by a light inextensible string of length 5 m. As a result, the centre of gravity of the block is found to rise a vertical distance of 10 cm. The speed of the bullet after it emerges out horizontally from the block will be
HARD
A block of mass m=0.1 kg is connected to a spring of unknown spring constant k. It is compressed to a distance x from its equilibrium position and released from rest. After approaching half the distance x2 from the equilibrium position, it hits another block and comes to rest momentarily, while the other block moves with velocity  3 m s-1. The total initial energy of the spring is: