1
JEE Main 2016 (Online) 9th April Morning Slot
+4
-1
Figure shows elliptical path abcd of a planet around the sun S such that the area of triangle csa is $${1 \over 4}$$ the area of the ellipse. (See figure) With db as the semimajor axis, and ca as the semiminor axis. If t1 is the time taken for planet to go over path abc and t2 for path taken over cda then :

A
t1 = t2
B
t1 = 2t2
C
t1 = 3t2
D
t1 = 4t2
2
JEE Main 2016 (Offline)
+4
-1
A satellite is revolving in a circular orbit at a height $$'h'$$ from the earth's surface (radius of earth $$R;h < < R$$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth's gravitational field, is close to : (Neglect the effect of atmosphere.)
A
$$\sqrt{2 g R}$$
B
$$\sqrt{g R}$$
C
$$\sqrt{g R / 2}$$
D
$$\sqrt{g R}(\sqrt{2}-1)$$
3
JEE Main 2015 (Offline)
+4
-1
From a solid sphere of mass $$M$$ and radius $$R,$$ a spherical portion of radius $$R/2$$ is removed, as shown in the figure. Taking gravitational potential $$V=0$$ at $$r = \infty ,$$ the potential at the center of the cavity thus formed is:
($$G=gravitational$$ $$constant$$)
A
$${{ - 2GM} \over {3R}}$$
B
$${{ - 2GM} \over R}$$
C
$${{ - GM} \over {2R}}$$
D
$${{ - GM} \over R}$$
4
JEE Main 2014 (Offline)
+4
-1
Four particles, each of mass $$M$$ and equidistant from each other, move along a circle of radius $$R$$ under the action of their mutual gravitational attraction. The speed of each particle is :
A
$$\sqrt {{{GM} \over R}}$$
B
$$\sqrt {2\sqrt 2 {{GM} \over R}}$$
C
$$\sqrt {{{GM} \over R}\left( {1 + 2\sqrt 2 } \right)}$$
D
$${1 \over 2}\sqrt {{{GM} \over R}\left( {1 + 2\sqrt 2 } \right)}$$
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