Orbits, Tides, and the Acceleration of Gravity

Question 1

What is total orbital energy?

Answer 1

Gravitational + kinetic energy. It stays constant if there is no external force

Question 2

Can orbits change spontaneously?

Answer 2

No

Question 3

What can make an object gain or lose orbital energy?

Answer 3

Friction, atmospheric drag, or a gravitational encounter

Question 4

What might happen if an object gains enough orbital energy?

Answer 4

It may escape (change from a bound to an unbound orbit). Escape velocity from earth is about 11 km/s from sea level

Question 5

How does gravity cause tides?

Answer 5

Moons gravity pulls harder on near side of the earth. Difference in moons gravitational pull stretches earth

Question 6

What is tidal friction?

Answer 6

Gradually slows earths rotation and makes the moon get farther from earth. The moon once orbitted at either a faster or slower speed, but tidal friction caused it to lock in synchronous rotation

Question 6

How do you change an orbit?

Answer 6

Change in total energy

Question 7

Why do all objects fall at the same rate?

Answer 7

Mass of object in Newtons second law cancels out mass in law of gravitation