TP 12.2

Given: m1 = 6.10 kg

            m2 = 7.20 kg

            r = 0.750 m

(a) Find:  F - ?

F = G m1m2 /r2

F =  (6.67 x 10-11 N-m2/kg2)(6.10 kg)(7.20 kg) /(0.750 m)2  = 521 x 10-11 N = 5.21 x 10-9 N

(b) Given that F = 2.00 x 10-9 N, find r - ? 

F = G m1 m2 /r2

r2 = G m1 m2 /F

r = (G m1 m2 /F)1/2

r = ((6.67 x 10-11 N-m2/kg2)(6.10 kg)(7.20 kg)/(2.00 x 10-9 N))1/2 = 1.21 m