How Come The Moon Is So Strong

[fatgaz]

hi peeps,
thought of this last night while in bed and could not think of an answer so could not get back to sleep, please help me me sleep tonite, right.......while on the moon the astronaughts could jump quite high because the gravity is only aprox 1 sixth of the earths gravity, soooooooo, if the moons gravity is only 1 sixth of the earth's how can it affect the oceans and cause tides ??, please any answers in laymans terms if poss, thanks in advance for any replies

[ToraToraTora]

The moon and earth are tidally locked and together they cause the tides. The water facing the moon bulges towards the moon but also the water on the other side of the earth bulges away from the moon.
explained here: https://scijinks.gov/tides/

[ToraToraTora]

... another question might be, if the moon is 100th the size of the Earth how come it has gravity of 1/6th? ....it's to do with R.

[THECORBYLOON]

Do you mean it's 1/100th the mass or 1/100th the diameter?

Regarding its gravity being, "to do with R[adius]", what about its mass?

[bednobs]

isnt the difference between the gravity the moon exerts and the gravity the moon experiences?

[Peter Pedant]

easiest

just as it affects the astronauts, so it affects the tides.
It is just a question of arithmetic

Newton the inventor of all this had a similar difficulty. He realised that gravity was the cause 1665 in the plague year - but it took him another 20 y to write it down ( helped by Halley I think) 1687
beause he was using the wrong figure for the mass of the moon - (so the calculations didnt balance)

[drmorgans]

The Moon's mass is around 1/80th (0.0123) of Earth's.

[ToraToraTora]

"isnt the difference between the gravity the moon exerts and the gravity the moon experiences? " - no it's because g=GM/r²

[Peter Pedant]

earths gravity

https://www.dummies.com/article/academics-the-arts/science/physics/how-to-calculate-the-force-of-gravity-on-the-earths-surface-174057

ends with a coy - why measure it observationally when you can calculate it, so long as you know the mass of the earth