Question 5
A satellite launched with velocity VE just escapes the earth’s gravitational attraction.
Given that the radius of the earth is R, show that VE =
. [g= 10 m s-2]
Observation
This question was attempted by very few candidates whose performance was very poor.
The expected answer is:
To show that VE = 
KE = Gravitational Potential Energy
½m
= 
(1) OR P.E = K.E
= 
(½) mgR = ½mv2 (1)
But GM = gR2 v2 = 2gR (½)
= 
= 2 gR (½) 
(½)
= 
= 
(1) = 
(1)