Homework answers
1. In Newton’s insight, what did a falling apple have in
common with the Moon? The were both falling into
Earth
2. In what sense does the moon “fall”? The Moon is
always falling toward Earth, if it didn’t it would just go
where its momentum carries it, which is in a straight
line, away from the Earth
8. How does the force of gravity between tow bodies
change when the distance between them is doubled? It
becomes ¼ as strong do to the inverse square rule
9. How does the intensity of light, radiation and sound
change when a point source is twice as far away? It
becomes ¼ as strong do to the inverse square rule
• 10. Do you escape the Earth’s gravity if you’re
above the atmosphere? By being on the
moon? Defend your answers. You cannot
ever escape Earths gravity, it only becomes
less strong. As long as there are two masses
there is a gravitational force between them.
• 24. Calculate the force of gravity between the
Earth and Moon. 2.1x 1020N
• 25. Calculate the force of gravity between the
Earth and Sun. 3.6 X 1022N