Intensity I = 1.35 kW/m2 = 1350W/m2
SURFACE AREA OF EARTH IS A =?R2
R = 6370 km = 6370000 m
c = 2.998*108 m/s
a)
we know that radiation pressure if all the incident energy
isabsorbed is P = I/c
               P
= 1350 W/m2/ 2.998*108 m/s
=450.3*10-8 N/m2
Now force DUE TO RADIATION IS FR = P*A
                                                                =
(450.3*10-8 N/m2)*?*(6370000
m)2
                                                                =
5.74*108N
b)
Gravitational force due to the Sun is Fg =GMm/r2
G =6.67*10-11Nm2/kg2
  M = mass of sun = 2*1030 kg
m = mass of earth = 6*1024kg
r = distance between the sun and earth =1.5*1011m
Then Fg =
6.67*10-11*2*1030*6*1024/(1.5*1011)2
             =
35.57*1021N
