1
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A bullet, fired into a door gets embedded exactly at it's centre, causing the door to rotate about it's vertical axis, practically without friction, with an angular velocity of $0.625 \mathrm{rads}^{-1}$. The door is 1.0 m wide and weighs 12 kg . If the mass of the bullet is 10 g , find the speed with which it was fired. (Hint: The moment of inertia of the door about the vertical axis at one end is $\frac{M L^2}{3}$.

A

$645 \mathrm{~ms}^{-1}$

B

$342 \mathrm{~ms}^{-1}$

C

$124 \mathrm{~ms}^{-1}$

D

$500 \mathrm{~ms}^{-1}$

2
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

In the equation $X=G^{-1 / 2} h^{1 / 2} c^{5 / 2}$, where G- universal gravitation constant, $h$ - Planck's constant and c - velocity of light, the dimensions of X are that of

A

Stress

B

Energy

C

Upthrust

D

Momentum

3
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

Force constant of interatomic bond, in a certain element, is $7.1 \mathrm{Nm}^{-1}$. If the atom oscillates in SHM in a certain direction, what is its frequency?

Given: Mole weight of the given element is 108 g and Avagadro's number $=6.023 \times 10^{23} \mathrm{~g} \mathrm{~mol}^{-1}$

A

$3.45 \times 10^{22} s^{-1}$

B

$0.005 \times 10^{12} s^{-1}$

C

$1 \times 10^{12} s^{-1}$

D

$6.667 \times 10^{12} s^{-1}$

4
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A circular coil of radius $r=10 c m$ having 300 turns carries a current of 2 A . The coil is suspended vertically in a uniform magnetic field of strength 0.7 T . If the plane of the coil makes an angle $30^{\circ}$ with the magnetic field, the torque needed to prevent it from turning is:

A

11.42 Nm

B

1.1 Nm

C

22.84 Nm

D

5.71 Nm