Question

Astrology, that unlikely and vague pseudoscience, makes much of the position of the planets at the moment of birth. The only known force a planet exerts on earth is gravitational.(a) Calculate the gravitational force exerted on a 5.00 kg baby by a 130 kg father 0.200 m away at birth (assisting so he is close).

Answer 1

The gravitational force is given by Newton's law of gravitation:

`\begin{gathered} F=G(m_1m_2)/(r^2) \\ \text{ where:} \\ G\text{ is the gravitational constant }6.67*10^(-11) \\ m_1\text{ and }m_2\text{ are the masses of the objects } \\ r\text{ is the distance between the objects} \end{gathered}`

In this case the masses are 5 kg and 130 kg and the distance is 0.2 m; then we have:

`\begin{gathered} F=(6.67*10^(-11))((5)(130))/((0.2)^2) \\ F=1.084*10^(-6) \end{gathered}`

Therefore, the force exerted is

`1.084*10^(-6)\text{ N}`