Two identical spheres are placed in contact with each other. The force of gravitation between the spheres will be proportional to ($R =$ radius of each sphere)
$R$
${R^2}$
${R^4}$
None of these
A satellite can be in a geostationary orbit around a planet at a distance $r$ from the centre of the planet. If the angular velocity of the planet about its axis doubles, a satellite can now be in a geostationary orbit around the planet if its distance from the centre of the planet is
When a body is taken from pole to the equator its weight
In a satellite if the time of revolution is $T$, then $P E$ is proportional to ..........
The masses and radii of the earth and the moon are $M_1, R_1$ and $M_2, R_2$ respectively. Their centres are distance $d$ apart. The minimum speed with which particle of mass $m$ should be projected from a point midway between the two centres so as to escape to infinity is
The value of $g$ at the surface of earth is $9.8 \,m / s ^2$. Then the value of ' $g$ ' at a place $480 \,km$ above the surface of the earth will be nearly .......... $m / s ^2$ (radius of the earth is $6400 \,km$ )