EASY
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Arjun wants to lift the rock as shown in the figure. At which point should he apply the force so that he could lift the rock easily?

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Important Questions on Matter

MEDIUM
A particle of mass m is moving along a trajectory given by
x=x0+a cosω1t
y=y0+b sinω2t
The torque, acting on the particle about the origin, at t=0 is:
MEDIUM
A solid cylinder of mass 2 kg and radius 4 cm is rotating about its axis at the rate of 3 rpm. The torque required to stop after 2π revolutions is
MEDIUM
A metal coin of mass 5 g and radius 1 cm is fixed to a thin stick AB of negligible mass as shown in the figure. The system is initially at rest. The constant torque, that will make the system rotate about AB at 25 rotations per second in  5 s , is close to:
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EASY
Find the torque about the origin when a force of 3j^ N acts on a particle whose position vector is 2k^ m.
MEDIUM
A slender uniform rod of mass M and length l is pivoted at one end so that it can rotate in a vertical plane (see figure). There is negligible friction at the pivot. The free end is held vertically above the pivot and then released. The angular acceleration of the rod when it makes an angle θ with the vertical is:

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MEDIUM
A square loop of side 2a and carrying current I is kept in xz plane with its centre at origin. A long wire carrying the same current I is placed parallel to z-axis and passing through point 0, b, 0, b>>a. The magnitude of torque on the loop about z-axis will be :
EASY
A solid cylinder of mass 50 kg and radius 0.5 m is free to rotate about horizontal axis. A massless string is wound round the cylinder with one end attached to it and other hanging freely. Tension in the string required to produce an angular acceleration of 2 revolutions s-2
EASY
Torque per unit moment of inertia is equal to
EASY
In a physical balance working on the principle of moments, when 5mg weight is placed on the left pan, the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct?
EASY
A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N?
HARD

A uniform rod of length l and mass m is free to rotate in a vertical plane about A. The rod initially in horizontal position is released. The initial angular acceleration of the rod is (Moment of inertia of rod about A is ml23)

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HARD
Consider a body of mass 1.0kg at rest at the origin at time t=0. A force F=αti^+βj^ is applied on the body, where α=1.0Ns-1 and β=1.0 N. The torque acting on the body about the origin at time =1.0 s is τ. Which of the following statements is (are) true?
MEDIUM

A mass m is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, then with what acceleration will the mass release? (Assume g= acceleration due to gravity)

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HARD

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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EASY
A light rope is wound around a hollow cylinder of mass 4 kg and radius 40 cm. If the rope is pulled with a force of 40 N, its angular acceleration is______.
EASY
If force F=3i^+4j^-2k^ acts on a particle having position vector 2i^+j^+2k^ then, the torque about the origin will be:
EASY
The dimensional formulaML2 T-2represents
HARD
A wheel of radius R and mass M is placed at the bottom of a fixed step of height R as shown in the figure. A constant force is continuously applied on the surface of the wheel so that it just climbs the step without slipping. Consider the torque τ about an axis normal to the plane of the paper passing through the point Q. Which of the following options is/are correct?

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HARD
An automobile moves on a road with a speed of 54 km h-1 . The radius of its wheels is 0.45m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2 . If the vehicle is brought to rest in 15 s , the magnitude of average torque transmitted by its brakes to the wheel is:
MEDIUM
To mop-clean a floor, a cleaning machine presses a circular mop of radius R vertically down with a total force F and rotates it with a constant angular speed about its axis. If the force F is distributed uniformly over the mop and if coefficient of friction between the mop and the floor is μ, the torque, applied by the machine on the mop is: