1
JEE Main 2020 (Online) 6th September Morning Slot
+4
-1
Four point masses, each of mass m, are fixed at the corners of a square of side $$l$$. The square is rotating with angular frequency $$\omega$$, about an axis passing through one of the corners of the square and parallel to its diagonal, as shown in the figure. The angular momentum of the square about this axis is :
A
3m$$l$$2$$\omega$$
B
4m$$l$$2$$\omega$$
C
m$$l$$2$$\omega$$
D
2m$$l$$2$$\omega$$
2
JEE Main 2020 (Online) 6th September Morning Slot
+4
-1
Shown in the figure is a hollow icecream cone (it is open at the top). If its mass is M, radius of its top, R and height, H, then its moment of inertia about its axis is :
A
$${{M\left( {{R^2} + {H^2}} \right)} \over 3}$$
B
$${{M{R^2}} \over 2}$$
C
$${{M{R^2}} \over 3}$$
D
$${{M{H^2}} \over 3}$$
3
JEE Main 2020 (Online) 5th September Evening Slot
+4
-1
A ring is hung on a nail. It can oscillate, without slipping or sliding
(i) in its plane with a time period T1 and,
(ii) back and forth in a direction perpendicular to its plane,
with a period T2. The ratio $${{{T_1}} \over {{T_2}}}$$ will be :
A
$${{\sqrt 2 } \over 3}$$
B
$${2 \over {\sqrt 3 }}$$
C
$${2 \over 3}$$
D
$${3 \over {\sqrt 2 }}$$
4
JEE Main 2020 (Online) 5th September Morning Slot
+4
-1
A wheel is rotating freely with an angular speed $$\omega$$ on a shaft. The moment of inertia of the wheel is I and the moment of inertia of the shaft is negligible. Another wheel of moment of inertia 3I initially at rest is suddenly coupled to the same shaft. The resultant fractional loss in the kinetic energy of the system is :
A
0
B
$${5 \over 6}$$
C
$${1 \over 4}$$
D
$${3 \over 4}$$
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