35
votes
7answers
5k views

Are we slightly lighter during the day and slightly heavier at night, owing to the force of the Sun's gravity?

Using $g = \frac{Gm}{r^2}$, the force on a point mass located at 1 AU from the Sun ($m = 2 \cdot 10^{30} \text{ kg}$) is about ~0.006 N/kg. Does that mean that, e.g., a 70 kg person is ~42g lighter ...
0
votes
1answer
48 views

Simple question about the tidal force (Leibniz's notation confuses me)

I started going through Taylor and Wheeler's Spacetime physics (standard textbook on special relativity). This is from exercise 2.8. Basically we're dropping a bearing ball from a 315 m height above ...
-1
votes
1answer
95 views

Lunar and solar tides [closed]

I just read the following statement in a book: If the diameter of the earth increased by 20%, both lunar and solar tides would be weakened with lunar tides weakening more than solar tides. What ...
3
votes
1answer
57 views

Question about tide

Let's say a canal is built in the middle of Kansas in the shape of a ring that stretches 100 miles in diameter. The band of water is 100 feet wide and 10 feet deep throughout the entire canal, and the ...
1
vote
1answer
93 views

Relationship between angular momentum of Earth and recession rate of the Moon

So the problem goes like this: Two masses $m_1$ and $m_2$ orbit each other with semimajor axis $a$. The orbit is circular, and $m_1 \gg m_2$. The body $m_1$ has a rotational moment of intertia $I_1$ ...