Kinetic energy needed to project a body of mass m from earth's surface (radius R ) to inf

English

Gujarati

Hindi

7.Gravitation

normal

The kinetic energy needed to project a body of mass $m$ from the earth's surface (radius $R$ ) to infinity is

A

$\frac {mgR}{2}$

B

$2mgR$

C

$mgR$

D

$\frac {mgR}{4}$

Solution

$ – \frac{{G{M_E}m}}{R}\, + \,K.E\, = \,0\, + \,0$

$K.E = \frac{{G{M_E}m}}{R}\, = \,\frac{{GMe}}{{{R^2}}}.mR\, = \,mgR$

Standard 11

Physics

Share

Similar Questions

A body weighs $700\,gm\,wt.$ on the surface of the earth. How much will it weigh on the surface of a planet whose mass is $\frac {1}{7}$ and radius half of that of the earth ……. $gm\, wt$

normal

A clock $S$ is based on oscillation of a spring and a clock $P$ is based on pendulum motion. Both clocks run at the same rate on earth. On a planet having the same density as earth but twice the radius

normal

If $R$ is the radius of earth and $g$ is the acceleration due to gravity on the earth's surface. Then mean density of earth is ……….

normal

The variation of acceleration due to gravity $ ( g )$ with distance $(r)$ from the center of the earth is correctly represented by … (Given $R =$ radius of earth)

normal

Which of the following statements are true about acceleration due to gravity?

$(a)\,\,'g'$ decreases in moving away from the centre if $r > R$

$(b)\,\,'g'$ decreases in moving away from the centre if $r < R$

$(c)\,\,'g'$ is zero at the centre of earth

$(d)\,\,'g'$ decreases if earth stops rotating on its axis

normal