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Saturday, May 15, 2010

Moon tidal foece on earth

hi
please see the link fortidal force calculation
http://www.themcdonalds.net/richard/astro/papers/602-tides-web.pdf
please note the amount of tidal forces mentioned below.
1)Moon feels from Earth-------(1.82)*(10)raised to 18 N
2)Earth feels from Moon-------(6.69)*(10)raised to 18 N
3)Earth feels from Sun---------(3.02)*(10)raised to 18 N
please note that the tidal force of Moon on Earth is more (3.5times) than ,the force of Earth on Moon.This is because Earth is bigger and hence bigger differential force.
Now,the question is -
If we (scientists) agrees that the Moonquakes are mainly due to tidal force of Earth,How and why we do not believe that the Moon can trigger tidal force induced earthquakes(which is 3.5 times more)?
If any one have specifice reason ,please let me know
regards
Amit

6 comments:

Roger Hunter said...

Amit;

Maybe this will help.


http://cseligman.com/text/moons/earthmoongravity.htm

The total force that the Earth and Moon exert on each other must be equal; but that does not mean that the effects of those equal forces must be the same, because the two objects have very different masses. The Earth is 81.6 times more massive than the Moon, and as a result, a given force will affect (or change) its motion 81.6 times less than it would the Moon. The obvious effect of the Earth's pull on the Moon is that the Moon orbits the Earth once every 27.3 days, moving in an elliptical path with a size of about 240,000 miles. The less obvious effect of the Moon's pull on the Earth is that the Earth also "orbits" the Moon every 27.3 days, though with an elliptical path 81.6 times smaller than that of the Moon, or only 3,000 miles in size.

Roger

AMIT said...

ROGER
Gravitational pull and tidal force are two different things.Gravitational pull of Moon to earth is same both ways and is equal to product of masses (considering both as point masses)divided by square of the distance(Newtons law)
However tidal force is a differential vector pull caused by radius of the planets

(m1*m2)
F=G --------- for farthest point
2
(R+w)

where R is center to center distance and w s radius of earth.
For point closest to Moon it is
2
(R-W) in he formula.
Since earth have greater radius the differential force is 3.5 times
every one is requested to correct me if I am wrong
Regards
Amit

Roger Hunter said...

Amit;

Here's a thought problem for you.

We have a rat weighing 2 lbs and a man weighing 163 lbs.

We drop a 1 lb hammer on the rat and a 3.5 lb hammer on the man.

Who gets hurt?

The man gets hit with 3.5 times as much force as the rat but the man is 81 times bigger than the rat.

Get the point?

Roger

AMIT said...

Roger
Man will get hurt,because the rat will run away. Just joking !!!
Roger,the earthcrust is 35-70 kms where as Moon crust is 60 to 150 kms. Moon has thicker crust.
Average density of Moon is 3.35 where as that of Earth is 5.5(actually crust density of earth is only 3.0)
Now caclulate,which crust(per sq km) is stronger.
Moreover,erath crust have plate boundries and faults as weaker section to break which is not the case with Moon.
Thus ,though man apears to be big and strong,rat is rigid (and smart)
regards
Amit

Roger Hunter said...

Amit;

Rat is asleep. 8-)

Yes, earth's crust is thinner and fractured but it rests on a MUCH thicker mantle which is even stronger.

It takes enormous force to cause a quake on earth. The tide is trivial in comparison and only contributes to a few shallow quakes.

Roger

AMIT said...

hi
please see my web page for details and dates
http://earthquakeprediction.webs.com/

or a link provided at right hsnd side of this blog-monthly 7+ quake prediction-
Amit