Question

The radius of Earth is R. At what distance above Earth's surface will the acceleration of gravity be 4.9 m/s2 ?

Answer 1

Answer:

Answer

Acceleration due to gravity at height h is given by

g

h

=

(R+h)

2

GM

we know g=GM/R

2

=9.8m/s

2

so GM/2R

2

=4.9m/s

2

putting in g

h

=

(R+h)

2

GM

2R

2

GM

=

(R+h)

2

GM

⟹R+h=

2

R

h=0.414R, where R is the radius of earth.

Answer 2

Answer:

Acceleration due to gravity at height h is given by

g

h

=

(R+h)

2

GM

we know g=GM/R

2

=9.8m/s

2

so GM/2R

2

=4.9m/s

2

putting in g

h

=

(R+h)

2

GM

2R

2

GM

=

(R+h)

2

GM

⟹R+h=

2

R

h=0.414R, where R is the radius of earth.