Class 11

Science

Physics

Gravitation

A mass $m$ is placed inside a hollow sphere of mass M as shown in figure. The gravitaional force on mass $m$ is

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Let us assume that our galaxy consists of $2.5×10_{11}$ stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution ? Take the diameter of the Milky Way to be $10_{5}$ ly.

A satellite moves around the earth in a circular orbit with speed $v$. If $m$ is the mass of the satellite, its total energy is

Three point masses 'm' each are placed at the three vertices of an equilateral traingle of side 'a'. Find net gravitational force on any point mass.

A rocket is fired 'vertically' from the surface of mars with a speed of $2kms_{−1}$. If 20% of its initial energy is lost due to martian atmospheric resistance, how far (in km) will the rocket go from the surface of mars before returning to it ? Mass of mars = $6.4×10_{23}kg$; radius of mars = 3395 km; $G=6.67×10_{−11}Nm_{2}kg_{−2}$.

The numerical value of the angular velocity of rotation of the earth should be…….. Rad/s in order to make the effective acceleration due to gravity equal to zero.

Suppose the earth increases its speed of rotation . At what new time period will the weightof a body on the equator becomes zero? Take $g=10s_{2}m $ and radius of the earth $R=6400km$.

A body of mass $m$ is placed on the earth surface is taken to a height of $h=3R$, then, change in gravitational potential energy is

Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth$=6×10_{24}$kg and of the Sun$=2×10_{30}kg$. The average distance between the two is $1.5×10_{11}$m.