Jawabanmu

2014-08-22T13:36:17+07:00
R1 = r ---> F
r2 = 1/4r1 ---> x
 
F/x = (r2)^{2} / (r1)^{2}    ( Gaya F  berbanding balik dgn jarak r)
F/x = (1/4r)^{2} / r^{2}
F/x = 1/16r² / r²
F/x = 1/16 per 1
F/x = 1/16
F.16 = x
x = 16F

Jadi..
jawabannya = 16F