1
JEE Main 2021 (Online) 17th March Evening Shift
+4
-1
A geostationary satellite is orbiting around an arbitrary planet 'P' at a height of 11R above the surface of 'P', R being the radius of 'P'. The time period of another satellite in hours at a height of 2R from the surface of 'P' is _________. 'P' has the time period of 24 hours.
A
3
B
5
C
$$6\sqrt 2$$
D
$${6 \over {\sqrt 2 }}$$
2
JEE Main 2021 (Online) 16th March Evening Shift
+4
-1
Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km)
A
158.2 m
B
79.1 m
C
19.77 m
D
39.55 m
3
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
Assume that a tunnel is dug along a chord of the earth, at a perpendicular distance (R/2) from the earth's centre, where 'R' is the radius of the Earth. The wall of the tunnel is frictionless. If a particle is released in this tunnel, it will execute a simple harmonic motion with a time period :
A
$$2\pi \sqrt {{R \over g}}$$
B
$${g \over {2\pi R}}$$
C
$${{2\pi R} \over g}$$
D
$${1 \over {2\pi }}\sqrt {{g \over R}}$$
4
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
A planet revolving in elliptical orbit has :

A. a constant velocity of revolution.

B. has the least velocity when it is nearest to the sun.

C. its areal velocity is directly proportional to its velocity.

D. areal velocity is inversely proportional to its velocity.

E. to follow a trajectory such that the areal velocity is constant.

Choose the correct answer from the options given below :
A
D only
B
E only
C
C only
D
A only
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