1
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Two planets have masses M and 16 M and their radii are $$a$$ and 2$$a$$, respectively. The separation between the centres of the planets is 10$$a$$. A body of mass m is fired from the surface of the larger planet towards the smaller planet along the line joining their centres. For the body to be able to reach at the surface of smaller planet, the minimum firing speed needed is :
A
$$2\sqrt {{{GM} \over a}} $$
B
$$\sqrt {{{G{M^2}} \over {ma}}} $$
C
$${3 \over 2}\sqrt {{{5GM} \over a}} $$
D
$$4\sqrt {{{GM} \over a}} $$
2
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
A satellite is in an elliptical orbit around a planet P. It is observed that the velocity of the satellite when it is farthest from the planet is 6 times less than that when it is closest to the planet. The ratio of distances between the satellite and the planet at closest and farthest points is:
A
1 : 2
B
1 : 3
C
1 : 6
D
3 : 4
3
JEE Main 2020 (Online) 5th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
The acceleration due to gravity on the earth’s surface at the poles is g and angular velocity of the earth about the axis passing through the pole is $$\omega $$. An object is weighed at the equator and at a height h above the poles by using a spring balance. If the weights are found to be same, then h is (h << R, where R is the radius of the earth)
A
$${{{R^2}{\omega ^2}} \over {2g}}$$
B
$${{{R^2}{\omega ^2}} \over g}$$
C
$${{{R^2}{\omega ^2}} \over {8g}}$$
D
$${{{R^2}{\omega ^2}} \over {4g}}$$
4
JEE Main 2020 (Online) 5th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
The value of the acceleration due to gravity is g1 at a height h = $${R \over 2}$$ (R = radius of the earth) from the surface of the earth. It is again equal to g1 at a depth d below the surface of the earth. The ratio $$\left( {{d \over R}} \right)$$ equals :
A
$${5 \over 9}$$
B
$${1 \over 9}$$
C
$${7 \over 9}$$
D
$${4 \over 9}$$
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