EASY
JEE Main/Advance
IMPORTANT
Earn 100

A uniform metre stick having mass 400 g is suspended from the fixed supports through two vertical light strings of equal lengths fixed at the ends. A small object of mass 100 g is put on the stick at a distance of 60 cm from the left end. Calculate the tensions in the two strings.(g=10 m s-2)

Important Questions on Rotational Mechanics

EASY
JEE Main/Advance
IMPORTANT

Assuming frictionless contacts, determine the magnitude of external horizontal force P applied at the lower end for equilibrium of the rod as shown in figure. The rod is uniform and its mass is m.

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HARD
JEE Main/Advance
IMPORTANT
A uniform ladder having length 10.0 m and mass 24 kg is resting against a vertical wall making an angle of 53° with it. The vertical wall is smooth but the ground surface is rough. A painter weighing 75 kg climbs up the ladder. If he stays on the ladder at a point 2 m from the upper end, what will be the normal force and the force of friction on the ladder by the ground? What should be the minimum coefficient of friction between ground and ladder for the painter to work safely? (g=10 ms-2) 
HARD
JEE Main/Advance
IMPORTANT

In the system as shown in figure, AB is a uniform rod of mass 10 kg and BC is a light string which is connected between wall and rod, in vertical plane. There is block of mass 15 kg connected at B with a light string. [Take g=10 m s-2] (BC and BD are two different strings)

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(i) Tension in the string BC

(ii) Hinge force exerted on beam at point A

MEDIUM
JEE Main/Advance
IMPORTANT

A rod of negligible mass having length l=2 m is pivoted at its centre and two masses of m1=6 kg and m2=3 kg are hung from the ends as shown in figure.

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(a) Find the initial angular acceleration of the rod if it is horizontal initially.

(b) If the rod is uniform and has a mass of m3=3 kg. 

(i) Find the initial angular acceleration of the rod.

(ii) Find the tension in the supports to the blocks of mass 3 kg and 6 kg  (g=10 ms-2).

HARD
JEE Main/Advance
IMPORTANT

The uniform rod AB of mass m is released from rest when β= 60º. Assuming that the friction force between end A and the surface is large enough to prevent sliding, determine (for the instant just after release)

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(a) The angular acceleration of the rod

(b) The normal reaction and the friction force at A.

HARD
JEE Main/Advance
IMPORTANT

A uniform thin rod of length L is hinged about one of its ends and is free to rotate about the hinge without friction. Neglect the effect of gravity.A force F is applied at a distance x from the hinge on the rod such that force is always perpendicular to the rod. Find the normal reaction at the hinge as function of x, at the initial instant when the angular velocity of rod is zero.

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HARD
JEE Main/Advance
IMPORTANT

A solid cylinder of mass M=1 kg & radius R=0.5 m is pivoted at its centre & has three particles of mass m=0.1kg mounted at its perimeter in the vertical plane as shown in the figure. The system is initially at rest. Find the angular speed of the cylinder, when it has swung through 900 in anticlockwise direction. [Take g=10 m s-2]

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HARD
JEE Main/Advance
IMPORTANT

A rigid body is made of three identical uniform thin rods each of length L fastened together in the form of letter H. The body is free to rotate about a fixed horizontal axis AB that passes through one of the legs of the H. The body is allowed to fall from rest from a position in which the plane of H is horizontal. What is the angular speed of the body, when the plane of H is vertical. 

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