The tidal waves in the sea are primarily due to

Six point masses of mass $m$ each are at the vertices of a regular hexagon of side $l$. Calculate the net gravitational force on any one of the masses.

The change in the value of acceleration of the earth towards the sun,when the moon moves from the position of a solar eclipse to the position on the other side of the earth in line with the sun,is: (mass of the moon $= 7.36 \times 10^{22} \ kg$,radius of the moon's orbit $= 3.8 \times 10^8 \ m$).

Two stars of masses $m_1$ and $m_2$ are parts of a binary star system. The radii of their orbits are $r_1$ and $r_2$ respectively,measured from the centre of mass of the system. The magnitude of the gravitational force that $m_1$ exerts on $m_2$ is

We can shield a charge from electric fields by putting it inside a hollow conductor. Can we shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means?

An astronaut of mass $m$ is working on a satellite orbiting the Earth at a distance $h$ from the Earth's surface. The radius of the Earth is $R$,while its mass is $M$. The gravitational pull $F_G$ on the astronaut is