Question

A 45 kg object is 2.5 m from a 160 kg object. What is the force of gravity between the objects?

Answer 1

`7.69*10^-8 \ N`

Explanation:

We have to use Newton's law of universal gravitation, which states that

`F_g=(Gm_1m_2)/r^2`

`G` is the gravitational constant, which is `6.674*10^-11 \ N \ m^2 "/" kg^2`

`m_1` & `m_2` are the masses of the two bodies in kilograms

`r` is the distance between the two bodies in meters (for this case)

Plugging in,

`G=6.674*10^-11 \ N \ m^2 "/" kg^2`

`m_1=45kg`

`m_2=160kg`

`r=2.5m, :.r^2=6.25m^2`

`F_g=(6.674*10^-11 \ N \ m^2 "/" kg^2*45kg*160kg)/(6.25m^2)`

Combining,

`F_g=(6.674*10^-11 \ N \ m^2 "/" kg^2*7200kg^2)/(6.25m^2)`

Now, we can cancel,

`F_g=(6.674*10^-11 \ N \ cancel(m^2) "/" cancel(kg^2)*7200cancel(kg^2))/(6.25cancel(m^2))`

`F_g~~7.69*10^-8 \ N`