1
JEE Main 2021 (Online) 25th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A solid sphere of radius R gravitationally attracts a particle placed at 3R from its centre with a force F1. Now a spherical cavity of radius $$\left( {{R \over 2}} \right)$$ is made in the sphere (as shown in figure) and the force becomes F2. The value of F1 : F2 is

JEE Main 2021 (Online) 25th February Morning Shift Physics - Gravitation Question 120 English
A
36 : 25
B
41 : 50
C
50 : 41
D
25 : 36
2
JEE Main 2021 (Online) 25th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Two satellites A and B of masses 200 kg and 400 kg are revolving round the earth at height of 600 km and 1600 km respectively.

If TA and TB are the time periods of A and B respectively then the value of TB $$-$$ TA :

JEE Main 2021 (Online) 25th February Morning Shift Physics - Gravitation Question 117 English
[Given : radius of earth = 6400 km, mass of earth = 6 $$\times$$ 1024 kg]
A
1.33 $$\times$$ 103 s
B
4.24 $$\times$$ 102 s
C
3.33 $$\times$$ 102 s
D
4.24 $$\times$$ 103 s
3
JEE Main 2021 (Online) 25th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : The escape velocities of planet A and B are same. But A and B are of unequal mass.

Reason R : The product of their mass and radius must be same. M1R1 = M2R2

In the light of the above statements, choose the most appropriate answer from the options given below :
A
Both A and R are correct and R is the correct explanation of A
B
Both A and R are correct but R is NOT the correct explanation of A
C
A is correct but R is not correct
D
A is not correct but R is correct
4
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A body weights 49N on a spring balance at the north pole. What will be its weight recorded on the same weighing machine, if it is shifted to the equator?

[Use $$g = {{GM} \over {{R^2}}}$$ = 9.8 ms$$-$$2 and radius of earth, R = 6400 km.]
A
49 N
B
49.83 N
C
48.83 N
D
49.17 N
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