Moon's speed on its path around the Earth

[oemSpace]

Referring to following link, I would like to know on when moon's speed is the fastest and the slowest on its path around the Earth.

1) is Moon's speed the fastest at the perigee?

2) is Moon's speed the slowest at the apogee?

Does anyone have any suggestions?
Thanks in advance

"Lunar Libration

In addition to its counterclockwise orbit around Earth, the Moon rotates around its axis at a constant speed. Like all celestial objects with elliptical orbits, the Moon's speed varies on its path around the Earth. It speeds up when it is at its perigee and slows down when it is at the apogee. This means that at its perigee, the Moon's orbital speed is faster than its rotational speed."

https://www.timeanddate.com/astronomy/moon/lunar-perigee-apogee.html

[Drax Spacex]

The answers to 1 and 2 are yes based on Kepler's second law of planetary motion.   A radius vector joining the Moon and the Earth sweeps out equal areas in equal lengths of time.  For a given delta time, to maintain equal orbital sector area, the arclength traversed by the Moon must be longest at perigee and shortest at apogee; i.e. speed must be highest at perigee and lowest at apogee.

[oemSpace]

Do following 2 statements correct?

1) Moon is increasing speed from apogee to perigee

2) Moon is decreasing speed from perigee to apogee

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

[Newbie]

1 hour ago, oemSpace said:

Do following 2 statements correct?

1) Moon is increasing speed from apogee to perigee

2) Moon is decreasing speed from perigee to apogee

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

During the half of the Moon’s orbit that it is approaching us, the mutual gravitational pull of the Earth-Moon system accelerates the Moon, causing it to move faster, until at the closest point in its orbit, called its orbital perigee, the Moon is moving about 6% faster than its average motion. Similarly, during the half of the Moon’s orbit that it is moving away from us, our mutual gravitational pull of the Earth-Moon system decelerates the Moon, causing it to move slower, until at the furthest point in the orbit, called its orbital apogee, the Moon is moving about 6% slower than its average motion. In addition to these actual changes in velocity, there is an apparent change in the Moon’s motion caused by the fact that the Moon is closer or further from us.  When it is closer to the Earth any motion that it has looks faster in angular terms than when it is farther away. This effect causes another 6% apparent increase or decrease in the apparent velocity of the Moon’s motion in the sky, in addition to the actual change.

Part of an article from J.Mangum, National Radio Astronomy Observatory, part of NSF (US)

So yes, during the Moon's orbit it's motion decelerates as it moves away from the Earth, P to A and accelerates on its approach to Earth, A to P.

 

Edited October 3, 2021 by Newbie

[oemSpace]

Thanks, to everyone very much for suggestions (^v^)

[Drax Spacex]

Interestingly, Kepler's laws of planetary motion predated the theory of gravity.  Through years of extensive and careful observation and record keeping, he derived formulas to predict very accurately the future locations of the Moon and planets.  No gravity required.  Or dark matter.   Just data and math formulas to match the data.

[Archmonoth]

14 minutes ago, Drax Spacex said:

Interestingly, Kepler's laws of planetary motion predated the theory of gravity.  Through years of extensive and careful observation and record keeping, he derived formulas to predict very accurately the future locations of the Moon and planets.  No gravity required.  Or dark matter.   Just data and math formulas to match the data.

The data includes all the variables, maybe even things we don't know about yet. In my opinion Heisenberg did a disservice with his push for Matrix theory, because before his time, calculus was taught before algebra. Differential calculus can be used for any system, regardless of the known/unknown variables.  

5 hours ago, Newbie said:

So yes, during the Moon's orbit it's motion decelerates as it moves away from the Earth, P to A and accelerates on its approach to Earth, A to P.

 

Same with planets too!  Conservation of momentum means a variable in velocity. The Earth has an average velocity (calculated as total distance divided by time), but the actual velocity is different based on the position around the Sun (equinox/solstice) 

Edited October 3, 2021 by Archmonoth