If the moon has the gravitational pull to affect our tides?

Question

How come this force is not strong enough to hold an astronaut on its surface?

Thanks people. I think Daniel R explained it in the simplest form. I know the atsronauts didn't go flying off the surface - but they had to wear heavily weighted boots etc to help the gravitational pull - what I couldn't get my head round (as I'm only a thick Yorkshireman) was how such a weak force could have such an effect on our tides. Perhaps I should have worded the question a little better?

Answer 1

It is strong enough - the astronauts didn't go floating off. It is weaker, which is why they were able to take such big steps, but in order to leave the moon they had to take off in the lunar lander...

The interesting thing about gravity as a force is that it's quite weak compared to other forces like electromagnetism and the nuclear forces, but that it works over huge distances (unlike the other ones). This is why the moon has an effect on the earth, but at the same time we can easily counteract the effects of gravity - for example by standing up!

Answer 2

Simply that the mass of an astronaut is very small comared to the mass of the oceans therefore the force on them (weight) is much less.

Newton's law of universal gravitation
Isaac Newton's law of universal gravitation states the following:

Every point mass attracts every other point mass by a force directed along the line connecting the two. This force is proportional to the product of the masses and inversely proportional to the square of the distance between them:

where:

F is the magnitude of the (repulsive) gravitational force between the two point masses
G is the gravitational constant
m1 is the mass of the first point mass
m2 is the mass of the second point mass
r is the distance between the two point masses
Assuming SI units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in metres (m), and the constant G is approximately equal to 6.67 × 10−11 N m2 kg−2 (newtons times meters squared per kilogram squared).

It can be seen that the repulsive force F is always negative, which means that the net attractive force is positive. (This sign convention is adopted in order to be consistent with Coulomb's Law, where a positive force means repulsion between two charges.)




The gravitational force of the moon is one ten-millionth that of earth, but when you combine other forces such as the earth's centrifugal force created by its spin, you get tides.

The sun's gravitational force on the earth is only 46 percent that of the moon. Making the moon the single most important factor for the creation of tides.

The sun's gravity also produces tides. But since the forces are smaller, as compared to the moon, the effects are greatly decreased.

Tides are not caused by the direct pull of the moon's gravity. The moon is pulling upwards on the water while the earth is pulling downward. Slight advantage to the moon and thus we have tides.

Answer 3

Misconception. The moon does "hold" an astronaut to its surface. It's just that the moon, being smaller than the earth, has less gravitational pull on the astronaut than the earth does when he or she is on the earth's surface, so they jump around more freely, etc.

Gravitational pull comes from the mass of the respective bodies. The moon is very close to the earth in size and distance, so it can effect the tides on earth.

Answer 4

Fact: a refridgerater magnet has a million times more force than the gravity of the moon. There is no science that can conclusively explain the gravitational effects of the moon upon our bodies. But in your question you DO ask about its affect on our minds. If you think it affects other people including you,then it will. Your mind will make it so.

Answer 5

ummm dude are you serious?
the moon has more than enough gravity to hold astronauts on the surface. Did you watch the pictures from the moon landing?
did you see them driving around in the moon car?, did you see the lunar lander sitting on the surface? did the astronauts fly off into space?

I think what you are getting confused by, is the fact that the moons gravity is alot less than earths, about 1/6th.
so if you weigh 180 pounds on earth you would weigh only 30 pounds on the moon. ( you would stll have the same amount of mass though!)

because of the low gravity when you walk you tend to rise off the surface much more than earth, so the astronauts found it was easier to "hop" along the surface than walk.

here are some movies of the astronauts on the moon

http://btc.montana.edu/CERES/html/Weight/movies1.html

Answer 6

The moon has 1/7th the gravitational pull. The boots just stop astronauts getting bored waiting for gravity to work.

Answer 7

When the Moon was first formed and took up orbit around Earth, it was 18x larger in the sky than it is now, of course that was around 4 billion years or so ago. Alot has happened since. At that time, the tides would have been on the earth as well as the water!

Answer 8

It does! Moons gravity is roughly 1/6 to what it is on Earth - hence the reason why the astronuats seem to take such big leaps - their apparent weight on the moon is much less. Even smaller planetoids like the asteriod Ceres or Eros have gravity, albeit a very weak feild

Answer 9

the ocen is to huge and too heavy so it can be affected by moon's force but an astronaut is not too heavy , the ocen and astronaut mass ratio is bigger than they distance ratio from the moon , an enormous ocen has for example 10 km depth and it gets half of the area of the earths surface (example) so it heavier than an human

Answer 10

I believe it has to do with the mass of the object being affected by said gravitational pull.