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Re: [Phys-L] apparent weight



Defining the acceleration of the person as the time rate of change of the velocity of the person relative to a reference frame in which the sun is at rest at the origin and the earth is orbiting the origin once per year, you have it exactly backwards. The person's acceleration is greater than that of the center of the earth at midnight when the person is farther from the sun, and smaller than that of the center of the earth at noon when the person is closer to the sun.

-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf Of John
Clement
Sent: Wednesday, December 10, 2014 11:29 AM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] apparent weight

The lighter scale reading will happen for both the Sun above and the Sun
below, just as the Moon produces 2 tides. This simple analogy argument
might be helpful with students. The simple physics explanation is that since
you are closer to the Sun when above than the center of the Earth, you have
a greater acceleration toward the sun. When the sun is below the Earth is
accelerating more towards the sun than you are because it is closer to the
Sun. In both cases this results in a lower scale reading. I will leave the
complicated explanations to others, as they will confuse most students.
Unfortunately most simple accounts of the tides ignore the true effect and
just talk about the pull. It is a gradient effect.

Of course a simple bathroom scale would be inadequate for seeing this
effect, and a gym scale which is a balance would show no effect.

John M. clement
Houston, TX



If you stand on a sensitive scale, will you be slightly lighter at
noon (with the Sun above you and pulling opposite to Earth's gravity),
and slightly heavier at midnight (with the Sun below you and pulling
in the same direction as Earth's gravity)? Ignore any lunar effects.

This came up the other day, and nobody could really agree.
One side said no because the Earth is in freefall around the Sun, and
it is the Earth that pulls us to it. The other side said yes due to
tidal effects as seen in the oceans.

I searched online, and found the same conflicting arguments!

Can anyone help with this?

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