Three particles of equal mass $m$ are situated at the vertices of an equilateral triangle of side $l$. They are moving in a circle under the influence of their mutual gravitational interaction. Then their time period of revolution is directly proportional to

Which of the following symptoms is likely to afflict an astronaut in space? $(a)$ Swollen feet,$(b)$ Swollen face,$(c)$ Headache,$(d)$ Orientational problem.

$A$ spacecraft travels in a straight line from the Earth to the Moon. How will its weight change during this journey?

The dependence of the intensity of the gravitational field $(E)$ of the Earth on the distance $(r)$ from the center of the Earth is correctly represented by:

Consider a spherical gaseous cloud of mass density $\rho(r)$ in free space,where $r$ is the radial distance from its center. The gaseous cloud is made of particles of equal mass $m$ moving in circular orbits about the common center with the same kinetic energy $K$. The force acting on the particles is their mutual gravitational force. If $\rho(r)$ is constant in time,the particle number density $n(r) = \rho(r) / m$ is:
[$G$ is the universal gravitational constant]

If the height of a satellite from the surface of the Earth is increased,then its