Weight Measurement on Mutually Orbiting Planets

In summary, the conversation discusses the measurement of weight on rotating objects and how it relates to tidal gravity. The initial question is about whether the weight would be the same on opposite sides of two orbiting planets. The answer states that the difference in weight is greatest between the point where the other planet is at zenith or nadir and the horizon point, and this can be measured by precision gravimeters.
  • #1
Jonnyb42
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So at the end of the lengthy thread https://www.physicsforums.com/showthread.php?t=404650", a similar but new question of mine arose:

If you consider the Earth rotating, you can measure differences in weight at different points on the Earth (namely, the extremes being the poles and the equator.) I am assuming you know why, etc.
Now if you have two mutually orbiting planets, I wanted to verify that if you measured weight at the point on a planet facing the other planet, and compared it with the weight measured at the opposite side of the planet, they should be approximately the same. (Assuming the diameters of the planets are negligible compared to their separation)
Or also, I am verifying that their revolution does not affect this measurement.

P.S.
I am asking this because when I originally posted the above thread, I had in mind that that measurement was not the same, as if it were similar to a merry-go-round, however I recently realized that this shouldn't be so, and before I went on to think about it more I wanted to verify that I'm right.
 
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  • #2
Tidal gravity is measurable. The difference is greatest not between the zenith and nadir points but between the point at which the other planet is at zenith (or nadir) and a point where the other planet is on the horizon. For example, the tidal gravitational effects due to the Sun and Moon on the surface of the Earth vary by up to 0.3 milligal over time (a gal is 1 cm/s2), a quantity that is easily measurable by precision gravimeters.
 

1. How is weight measured on mutually orbiting planets?

The weight of an object is measured using the formula: W = mg, where W is weight, m is the mass of the object, and g is the acceleration due to gravity. On mutually orbiting planets, the value of g may differ due to variations in mass and distance from the planets' centers of gravity.

2. Is weight the same on mutually orbiting planets?

No, weight is not the same on mutually orbiting planets. As mentioned before, the value of g may differ due to variations in mass and distance from the planets' centers of gravity. This means that the weight of an object will also differ on each planet.

3. How does weight measurement on mutually orbiting planets affect space travel?

Weight measurement on mutually orbiting planets is crucial for space travel as it helps determine the amount of fuel needed for spacecraft to escape the planets' gravitational pull. It also affects the weightlessness experienced by astronauts in space, as the force of gravity is different on each planet.

4. Can weight be converted between mutually orbiting planets?

No, weight cannot be converted between mutually orbiting planets as it is a measure of the force of gravity on an object. However, mass can be converted between planets using the formula: m1/m2 = g2/g1, where m1 and m2 are the masses on each planet and g1 and g2 are the values of acceleration due to gravity.

5. How does weight measurement on mutually orbiting planets impact scientific research?

Weight measurement on mutually orbiting planets is essential for scientific research as it helps scientists understand the differences in gravitational forces on different planets. This information can also aid in the development of new technologies and spacecraft for space exploration.

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