1
JEE Main 2021 (Online) 27th August Morning Shift
MCQ (Single Correct Answer)
+4
-1
A huge circular arc of length 4.4 ly subtends an angle '4s' at the centre of the circle. How long it would take for a body to complete 4 revolution if its speed is 8 AU per second?

Given : 1 ly = 9.46 $$\times$$ 1015 m

1 AU = 1.5 $$\times$$ 1011 m
A
4.1 $$\times$$ 108 s
B
4.5 $$\times$$ 1010 s
C
3.5 $$\times$$ 106 s
D
7.2 $$\times$$ 108 s
2
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
The solid cylinder of length 80 cm and mass M has a radius of 20 cm. Calculate the density of the material used if the moment of inertia of the cylinder about an axis CD parallel to AB as shown in figure is 2.7 kg m2.

A
14.9 kg/m3
B
7.5 $$\times$$ 101 kg/m3
C
7.5 $$\times$$ 102 kg/m3
D
1.49 $$\times$$ 102 kg/m3
3
JEE Main 2021 (Online) 25th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : Moment of inertia of a circular disc of mass 'M' and radius 'R' about X, Y axes (passing through its plane) and Z-axis which is perpendicular to its plane were found to be Ix, Iy and Iz respectively. The respectively radii of gyration about all the three axes will be the same.

Reason R : A rigid body making rotational motion has fixed mass and shape. In the light of the above statements, choose the most appropriate answer from the options given below :
A
Both A and R are correct but R is NOT the correct explanation of A.
B
A is not correct but R is correct.
C
A is correct but R is not correct.
D
Both A and R are correct and R is the correct explanation of A.
4
JEE Main 2021 (Online) 22th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Consider a situation in which a ring, a solid cylinder and a solid sphere roll down on the same inclined plane without slipping. Assume that they start rolling from rest and having identical diameter.

The correct statement for this situation is
A
All of them will have same velocity.
B
The ring has greatest and the cylinder has the least velocity of the centre of mass at the bottom of the inclined plane.
C
The sphere has the greatest and the ring has the least velocity of the centre of mass at the bottom of the inclined plane.
D
The cylinder has the greatest and the sphere has the least velocity of the centre of mass at the bottom of the inclined plane.
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