Question

Calculate the force that earth's gravity exerts on a 1 kg mass at the following locations:

a) On the surface of the earth
b) 3 km above earth's surface
c) 300 km above earths surface
d) 30,000 km above earths surface

Please help me with the answers, I wasnt here when we learned this.

Answer 1

we all know when the exerts force on the body it becomes weight so
and weight is a force
so
force = m*g
whereas g= G * M / d^2
G= gravitational constent
M = mass of the earth
d = distence of the earth from centre
then the above formula becomes
f = G*M*m/d^2
as f= mg
m*g= G*M*m/d^2
m on both sides will cancel each other
g = G*M/d^2 1
where
value of G =6.673 * 10^-11 Nm^2
value of M = 5.98 * 10 ^24 kg
and
value of d at surface of earth is = 6.38 * 10^ 6
you can find the value by using this formula
g=g = G*M/d^2

Answer 2

3km above earth surface
g=GM/(R+h)^2
h=3000m

Answer 3

R = 6400 km

Answer 4

Ohhhh I'll use R=6400 with shamims equation?