Part I
The gravitational atractive force between Sally and the Earth is given by:
[tex]F=G\times\frac{m_{S\times}m_E}{r^2}[/tex]where:
G = gravitational constant =
[tex]G=6.67\times10^{-11}N.m^2kg^{-2}[/tex]ms = mass of Sally
mE = mass of the Earth
r = distance between Sally and the Earth, namely the radius of the Earth
Putting all the information in the formula above we get:
[tex]\begin{gathered} F=6.67\times10^{-11}\times\frac{45.9\times5.98\times10^{24}}{(6.38\times10^6)^2} \\ F=(1,830.79)\times\frac{10^{13}}{40.70\times10^{12}} \\ F=44.98\times10 \\ F\approx450N \end{gathered}[/tex]Part II
The weight of Sally is the intensity of gravitational force due to Earth. We calculate with the formula:
[tex]W=m\times g[/tex]where:
m = mass of Sally
g = acceleration of gravity = 9.8 m/s²
Putting the information in the formula, we have:
[tex]\begin{gathered} W=45.9\times9.8 \\ W=449.82 \\ W\approx450N\text{ } \end{gathered}[/tex]