Physics (Essay) Paper 2 WASSCE (SC), 2020

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 = j

                     KE = Gravitational Potential Energy
½mj = j             (1)        OR                  P.E = K.E       
j = j                    (½)                               mgR = ½mv2   (1)
But GM = gR2                                                     v2 = 2gR          (½)
j= j  =  2 gR      (½)                               j     (½)
j= j  = j    (1)                        = j       (1)