Answer
a) $F=2.7\times 10^{-11}N$
b) $F=6.8\times 10^{-12}N$
Work Step by Step
(a) According to Newton's universal law of gravity
$F=G\frac{m_1m_2}{r^2}$
We plug in the known values to obtain:
$F=6.67\times 10^{-11}\times\frac{0.16(0.16)}{(0.25)^2}$
$F=2.7\times 10^{-11}N$
(b) We know that
$F=G\frac{m_1m_2}{r^2}$
We plug in the known values to obtain:
$F=6.67\times 10^{-11}\times\frac{0.16(0.16)}{(0.50)^2}$
$F=6.8\times 10^{-12}N$
