MEDIUM
JEE Main
IMPORTANT
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Three point masses, each of mass m , are situated at the three corners of an equilateral triangle of each side l . The moment of inertia of this system about one of the sides of the triangle will be

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Important Questions on Rotational Motion

MEDIUM
JEE Main
IMPORTANT

The uniform rod of mass 20 kg and length 1.6 m is pivoted at its end and swings freely in the vertical plane. Angular acceleration of rod just after the rod is released from rest in the horizontal position as shown in figure is 

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MEDIUM
JEE Main
IMPORTANT

Uniform rod AB is hinged at the end A in a horizontal position as shown in the figure (the hinge is frictionless, that is, it does not exert any friction force on the rod). The other end of the rod is connected to a block through a massless string as shown. The pulley is smooth and massless. Masses of the block and the rod are same and are equal to m. Acceleration due to gravity is g. The tension in the thread and angular acceleration of the rod just after the release of block from this position.

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MEDIUM
JEE Main
IMPORTANT
A solid uniform disc of mass m rolls without slipping down an inclined plane with an acceleration a. The frictional force on the disc due to the surface of the plane is
MEDIUM
JEE Main
IMPORTANT

A small block of mass m is rigidly attached at P to a ring of mass 3m and radius r. The system is released from rest at θ=90° and rolls without sliding. The angular acceleration of the ring just after release is

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MEDIUM
JEE Main
IMPORTANT

A spherical rigid ball is released from rest and starts rolling down an inclined plane from height h=7 m, as shown in the figure. It hits a block at rest on the horizontal plane (assume elastic collision). If the mass of both the ball and the block is m and the ball is rolling without sliding, then the speed of the block after collision is close to 

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(take g=10 m s-2)

HARD
JEE Main
IMPORTANT
A circular disc of mass M and radius R is rotating about its axis with angular speed ω1. If another stationary disc having radius R2 and same mass M is droped co-axially on to the rotating disc. Gradually both discs attain constant angular speed ω2 the energy lost in the process is p% of the initial energy. Value of p is
HARD
JEE Main
IMPORTANT

Two masses M are moving perpendicular to the rod of mass M with velocities v and 2v as shown in the figure. The length of the rod is L. Find the ratio of the final velocity of the rod and its angular velocity if the masses stop at their place after collision.

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HARD
JEE Main
IMPORTANT
A hoop of radius r and mass m rotating with angular velocity ω0 is placed on a rough horizontal surface. The initial velocity of centre of the hoop is zero. What will be the velocity of the centre of the hoop when it ceases to slip?