Question

Two identical lead spheres with their centers 19 cm apart attract each other with a 0.30 μn force. find their mass.

Answer 1

$m_{1} =m_2$
$F_gravity$ = 0.30 μn = $(0.3)10^6$

Using Newton's Equation for universal gravitation we can derive the masses

$F_{g} = G \frac{ m_{1} m_2}{d^2}$
$F_{g} = G \frac{ 2m}{d^2}$
$2m=\frac{d^2( F_{g}) }{G}$
$m=\frac{d^2( F_{g}) }{2G}$
$m=\frac{0.019^2( 0.3)(10^6)}{2 (6.673 (10^{-11})}$
$m=\frac{0.019^2( 0.3)}{2 (6.673 (10^{-5})}$
$m= 0.8114 kg$