Answer
(a) The magnitude of the gravitational force exerted on the raindrop by the Earth is $5.1\times10^{-6}N$.
(b) The magnitude of the gravitational force exerted on the Earth by the raindrop is $5.1\times10^{-6}N$.
Work Step by Step
We have:
- The universal gravitational constant $G=6.67\times10^{-11}Nm^2/kg^2$
- Raindrop's mass $m_r=5.2\times10^{-7}kg$
- Earth's mass $M_E=5.98\times10^{24}kg$
- The distance between Earth and the raindrop (the Earth's radius) $r=6.38\times10^6m$.
The gravitational force exerted between Earth and the raindrop is $$F_g=G\frac{m_rM_E}{r^2}=5.1\times10^{-6}N$$
The magnitude of the gravitational force exerted on the raindrop by the Earth and the reverse are the same, both of which are $5.1\times10^{-6}N$.
