# A Rocket is Fired from the Earth Towards the Sun. at What Distance from the Earth’S Centre is the Gravitational Force on the Rocket Zero? Mass of the Sun = 2 ×1030 Kg, Mass of the Earth = 6 × 1024 Kg. Neglect the Effect of Other Planets Etc - Physics

A rocket is fired from the earth towards the sun. At what distance from the earth’s centre is the gravitational force on the rocket zero? Mass of the sun = 2 ×1030 kg, mass of the earth = 6 × 1024 kg. Neglect the effect of other planets etc. (orbital radius = 1.5 × 1011 m).

#### Solution 1

Mass of the Sun, Ms = 2 × 1030 kg

Mass of the Earth, Me = 6 × 10 24 kg

Orbital radius, r = 1.5 × 1011 m

Mass of the rocket = m

Let x be the distance from the centre of the Earth where the gravitational force acting on satellite P becomes zero.

From Newton’s law of gravitation, we can equate gravitational forces acting on satellite P under the influence of the Sun and the Earth as:

(GmM_s)/(r-x)^2 = GmM_e/x^2

((r-x)/x)^2 = M_s/M_e

(r-x)/r = ((2xx10^(30))/(60xx10^(24)))^(1/2) = 577.35

1.5 xx 10^(11)-x=577.35x

x = (1.5xx10^11)/578.35 = 2.59 xx 10^8 m

#### Solution 2

Mass of Sun, M = 2 x 1030 kg; Mass of Earth, m = 6 x 1024 kg Distance between Sim and Earth, r = 1.5 x 1011 m

Let at the point P, the gravitational force on the rocket due to Earth = gravitional force on the rocket due to sun

Let x = distance of the point { from the Earth

Then (Gm)/x^2 = (GM)/(r-x)^2

=>(r-x)^2/x^2 = M/m = (2xx10^(30))/(6xx10)^24 = 10^6/3

or (r-x)/x = 10^3/sqrt3 => r/x = 10^3/sqrt3 + 1 =~ 10^3/sqrt3

or x = (sqrt3r)/10^3 = (1.732xx1.5xx10^11)/10^3 = 2.6 xx 10^8 m

Is there an error in this question or solution?

#### APPEARS IN

NCERT Class 11 Physics Textbook
Chapter 8 Gravitation
Q 12 | Page 202