Weight change with rotation ?

by Gh778
Tags: rotation, weight
nicu is offline
Apr4-12, 10:40 AM
P: 13
G is an imitation of g and his formula and value are very doubtful...
Gh778 is offline
Apr4-12, 11:48 AM
P: 365
I have corrected

2*m*G*M*H/100*(1/(R-100)-1/(R)) = 1964.52227397479936678121

compared to

m*G*M/1*(-1/(R+1)+1/R-1/(R-1)+1/R) = +3.08348993657429924912e-6
m*G*M*H/100*(1/(R-99)-1/(R+1)+1/(R-101)-1/(R-1)) = 1964.52227397494456785185

m*G*M/1*((1/(R-99)-1/(R-100))+(1/(R-101)-1/(R-100))) = -0.08363513764493721675e-6

The sum is :

1964.52227397479936678121-3.08348993657429924912e-6-1964.52227397494456785185+3.08363513764493721675e-6 = 1e-27 it's ok, the sum is 0.

3/ The net gravitationnal force is in R 4 but the torque is in R 3 , how the sum of energy is 0 ?
How the sum can be to 0 ?
Gh778 is offline
Apr6-12, 05:34 AM
P: 365
I have thought about something I don't understand. When a screw is in water with bottom thread end with vertical surface. The torque on the bottom surface is canceled all along the thread with a differencial of pressure (up/down surface of the thread). With the pressure of water = f(h) it's ok, all torque are canceled, but now with pressure = f(h,Δh) why the bottom torque is not greater than the differencial torque ? The difference is not big but must be to 0 I think ?

NB. We are for example on Earth with gravity = 9.81 m/s. The screw can only turn.
Attached Thumbnails
Gh778 is offline
Apr6-12, 09:34 AM
P: 365
All is fine I understand the problem.

But for this thread I will calcultate if the torque is 0 :

A circular thread (can only turn) in sandwich between 2 circular fixed thread. Up and down small film of water. See the drawing. The thread has only film of water up and down.Normally, this thread don't turn because the height of water is the same. But really, one side is more far from Earth (the up side). This give a torque ?
Attached Thumbnails
circular thread.png  
Gh778 is offline
Apr6-12, 11:42 AM
P: 365
I drew the developpant of the helicoid (thread). This helicoid is in a sandwich between 2 fixed helicoids. Only film of water Up and Down surfaces.

The down torque = T1 = Radius_of_helicoid * Down_surface * density_of_water * height * Gt * Mt * ( g + (1/(R+250) - 1/R ) )

The up torque = T2 = Radius_of_helicoid * Up_surface * density_of_water * height * Gt * Mt * ( g + (1/(R+350) - 1/(R+100) ) )

g = 9.81
Mt = Mass of Earth
Gt = Gravitational constant
Up_surface = Down _surface
k = Radius_of_helicoid * Down_surface * density_of_water * height * Gt * Mt

T1 = k * ( g + (1/(R+250) - 1/R ) ) = 9.8099999999938410347 * k

T2 = k * ( g + (1/(R+350) - 1/(R+100) ) = 9.80999999999384122804 * k

There is a little difference ?
Attached Thumbnails
developpant of helicoid.png  
Gh778 is offline
Apr6-12, 05:08 PM
P: 365
I find the problem, the force is perpendiculary to the surface and movement.

Another question is with a fixed column of water with a fixed mass under it. Like the mass is more at left, the pressure at left in the column is higher than at right. The water move inside the column ? Or another force balance this ? (No other gravity, only mass M and water). Mass of M is 100 or higher than mass of water for example, because there are forces in water alone, the up of water attrack the down, idem for the sides, maybe already a movement in water alone.
Attached Thumbnails
column of water with mass M.png  

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