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Four identical solid spheres each of mass m and radius a are placed with their centres on the four corners of a square of side b. The moment of inertia of the system about one side of square where the axis of rotation is parallel to the plane of the square is :

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Important Questions on Rotational Motion

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JEE Main
IMPORTANT
A cord is wound round the circumference of wheel of radius r, The axis of the wheel is horizontal and the moment of inertia about it is I. A weight mg is attached to the cord at the end. The weight falls from rest. After falling through a distance h, the square of angular velocity of wheel will be
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JEE Main
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Two masses A and B, each of mass M are fixed together by a massless spring, A force acts on the mass B as shown in figure. If the mass A starts moving away from mass B with acceleration a, then the acceleration of mass B will be :

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MEDIUM
JEE Main
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A bead of mass m stays at point Pa, b on a wire bent in the shape of a parabola y=Cx2 and rotating with angular speed ω (see figure). The value of ω is (neglect friction)

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Shown in the figure is rigid and uniform one meter long rod AB held in horizontal position by two strings tied to its ends and attached to the ceiling. The rod is off mass 'm' and has another weight of mass 2 m hung at a distance of 75 cm from A. The tension in the string at A is:

 

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HARD
JEE Main
IMPORTANT

A uniform cylinder of mass M and radius R is to be pulled over a step of height aa<R by applying a force F at its centre 'O' perpendicular to the plane through the axes of the cylinder on the edge of the step (see figure). The minimum value of F required is:

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MEDIUM
JEE Main
IMPORTANT
Two uniform circular discs are rotating independently in the same direction around their common axis passing through their centres. The moment of inertia and angular velocity of the first disc are 0.1 kg-m2 and 10 rad s-1 respectively while those for the second one are  0.2 kg-m2 and 5 rad s-1 respectively. At some instant they get stuck together and start rotating as a single system about their common axis with some angular speed. The kinetic energy of the combined system is :
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JEE Main
IMPORTANT

A square shaped hole of side l= a2 is carved out at a distance d=a2 from the centre O of a uniform circular disk of radius a. If the distance of the centre of mass of the remaining portion from O is -ax, value of x (to the nearest integer) is :

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JEE Main
IMPORTANT
Moment of inertia of a cylinder of mass m, length L and radius R about an axis passing through its centre and perpendicular to the axis of the cylinder is I=MR24+L212. If such a cylinder is to be made for a given mass of a material, the ratio LR for it to have minimum possible I is: