jbriggs444's latest activity
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jbriggs444 replied to the thread Graduate Please Explain Elementary Physics Elevator Question.I would accept that. Gravity is the force of gravity. It is given by ##F_g = \frac{Gm_1m_2}{r^2}##. It acts on ##m_1## in the direction... -
Polaris is "up" from the north pole. North is a direction along the surface of the Earth.
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One possibility, known as the Hartle-Hawking no boundary proposal, is that if you go backward in time towards the big bang, you reach a...
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jbriggs444 reacted to PeterDonis's post in the thread Undergrad Where did the early photons go? with
Like.
A subthread on how the "speed of expansion" of a material object is defined has been moved to a separate thread in the relativity forum... -
jbriggs444 reacted to Baluncore's post in the thread High School 'splain this hydrostatic paradox in tiny words with Like.
By hiding some important details, they would get more clicks on the video. I expect identical glass pistons, that press on the scale...
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jbriggs444 replied to the thread High School 'splain this hydrostatic paradox in tiny words.I assume that the mechanism includes some sort of identical pistons inside the vertical glass walled tubing. The scale pans are then...
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jbriggs444 replied to the thread High School Why Do Events Freeze For Me at the Speed of Light?.Yes, there is a last instant of your home world's future that you will ever see. However, this last instant is not seen when you reach...
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jbriggs444 reacted to Ibix's post in the thread Undergrad Where did the early photons go? with Like.
There is no perimeter. As far as we are aware the universe is either infinite in size or closed and boundaryless (like the surface of a...
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jbriggs444 replied to the thread Undergrad Where did the early photons go?.We start by laying down a "co-moving" coordinate system. In this coordinate system the universe at a particular time is homogeneous. We...
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jbriggs444 replied to the thread Undergrad Where did the early photons go?.Density, for one thing.
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jbriggs444 replied to the thread Undergrad Where did the early photons go?.According to our accepted theories there is no edge. Just more approximately homogeneous universe in every direction. The "diameter of...
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https://en.wikipedia.org/wiki/Statically_indeterminate
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jbriggs444 replied to the thread Correct statement about siphon used to empty water tank.At room temperature the saturated vapor pressure of water is about 3% of an atmosphere. Whether this counts as "approximately zero"...
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jbriggs444 replied to the thread High School The Effect of Linear and Rotational Motion on Measured Weight.On the contrary, I would expect an effect for all circle sizes. The effect would gradually increase as the diameter of the circle...
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jbriggs444 replied to the thread Correct statement about siphon used to empty water tank.[Water] siphons stop working at about 0 C.
