1
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
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 :
A
$${k \over {4I}}\theta$$
B
$${k \over {I}}\theta$$
C
$${k \over {2I}}\theta$$
D
$${2k \over {I}}\theta$$
2
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
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 :-
A
$$\sqrt {{{qE} \over {md}}}$$
B
$$\sqrt {{{qE} \over {2md}}}$$
C
$$\sqrt {{{qE} \over {-2md}}}$$
D
$$\sqrt {{{2qE} \over {md}}}$$
3
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
A rectangular solid box of length 0.3 m is held horizontally, with one of its sides on the edge of a platform of height 5m. When released, it slips off the table in a very short time t = 0.01s, remaining essentially horizontal. The angle by which it would rotate when it hits the ground will be (in radians) close to :-
A
0.28
B
0.02
C
0.3
D
0.5
4
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
Four particles A, B, C and D with masses mA = m, mB = 2m, mC = 3m and mD = 4m are at the corners of a square. They have accelerations of equal magnitude with directions as shown. The acceleration of the centre of mass of the particles is :
A
$${a \over 5}\left( {\mathop i\limits^ \wedge + \mathop j\limits^ \wedge } \right)$$
B
$${a \over 5}\left( {\mathop i\limits^ \wedge - \mathop j\limits^ \wedge } \right)$$
C
$${a }\left( {\mathop i\limits^ \wedge + \mathop j\limits^ \wedge } \right)$$
D
Zero
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