JEE Main 2019 (Online) 9th April Evening Slot | Rotational Motion Question 109 | Physics

JEE Main 2019 (Online) 9th April Evening Slot

MCQ (Single Correct Answer)

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Moment of inertia of a body about a given axis is 1.5 kg m². Initially the body is at rest. In order to produce a rotational kinetic energy of 1200 J, the angular accleration of 20 rad/s² must be applied about the axis for a duration of :-

2.5 s

3 s

2 s

JEE Main 2019 (Online) 9th April Evening Slot

MCQ (Single Correct Answer)

-1

A thin smooth rod of length L and mass M is rotating freely with angular speed $$\omega $$₀ about an axis perpendicular to the rod and passing through its center. Two beads of mass m and negligible size are at the center of the rod initially. The beads are free to slide along the rod. The angular speed of the system , when the beads reach the opposite ends of the rod, will be :-

$${{M{\omega _0}} \over {M + 3m}}$$

$${{M{\omega _0}} \over {M + m}}$$

$${{M{\omega _0}} \over {M + 6m}}$$

$${{M{\omega _0}} \over {M + 2m}}$$

JEE Main 2019 (Online) 9th April Morning Slot

MCQ (Single Correct Answer)

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A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of $$\theta $$, where $$\theta $$ is the angle by which it has rotated, is given as k$$\theta $$². If its moment of inertia is I then the angular acceleration of the disc is :

$${k \over {4I}}\theta $$

$${k \over {I}}\theta $$

$${k \over {2I}}\theta $$

$${2k \over {I}}\theta $$

JEE Main 2019 (Online) 8th April Evening Slot

MCQ (Single Correct Answer)

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An electric dipole is formed by two equal and opposite charges q with separation d. The charges have same mass m. It is kept in a uniform electric field E. If it is slightly rotated from its equilibrium orientation, then its angular frequency $$\omega$$ is :-

$$\sqrt {{{qE} \over {md}}} $$

$$\sqrt {{{qE} \over {2md}}} $$

$$\sqrt {{{qE} \over {-2md}}} $$

$$\sqrt {{{2qE} \over {md}}} $$

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