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What is the amount of force applied on my back while I'm brushing teeth leaning forward?

The vertebrae column is a wonderous contraption full of balances, tensegrity, and organics. As such, it is a daunting challenge to predict its behaviors, even at a PhD level of physics, much less ...
Cort Ammon's user avatar
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3 votes

How far can we go in space?

But actually it is quite possible to go far in less than a life time, from the traveller's point of view, due to relativity, Your final conclusion is correct. Working on these two specifications: ...
KDP's user avatar
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10 votes
Accepted

How far can we go in space?

Since your objective is to go as far as possible, rather than rendezvous with a particular destination, then I will assume you do not need the spaceship to decelerate. The best way to utilise the ...
gandalf61's user avatar
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6 votes

Is it plausible that Earth's magnetism can induce heart attacks by affecting red blood cells?

Is it plausible that Earth's geomagnetism causes the rate of heart attacks to double? No, it is not even remotely plausible. First, a doubling in the rate of heart attacks is huge. You would expect ...
Dale's user avatar
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1 vote

Is it plausible that Earth's magnetism can induce heart attacks by affecting red blood cells?

I am going to say no that it is not plausible or likely simply because every single cell in the human body has a cellular wall around it that acts as an insulator for the cell itself and even though a ...
Richard Morgan's user avatar
2 votes

Temperature estimation based on very quick measurements

Unfortunately, back-calculating peak temperatures using measurements in the present is mathematically ill-defined- that is, there are many earlier temperatures which will result in the present ...
niels nielsen's user avatar
1 vote

Temperature estimation based on very quick measurements

It sounds like $r = 5$ ms for your thermocouple. You are on the right track, except that it might not be practical. For example, quickly transferring a thermocouple from one container to another in $&...
mmesser314's user avatar
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-1 votes

What's the formula for the speed of an accelerating car?

In Excell: Vmax * (1-1/(EXP(A*B(t)))) Where Vmax is the auto max speed. A is the time in seconds. B(t) is an equation which approximates the change in drag. You need 3 data points: At time zero speed ...
NoBody's user avatar
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1 vote

How to obtain the center of mass energy needed to form a black hole in a particle accelerator?

At CERN routine proton-proton collision energies are about 13Tev. In 2018 they switched to lead ion collisions. These collisions had an collision energy of about 5.36 Tev per nucleon pair and a lead ...
KDP's user avatar
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1 vote

How to obtain the center of mass energy needed to form a black hole in a particle accelerator?

Here are some physical arguments ... The particle energies at CERN give us an upper limit on the mass of any black holes that could possibly be created. And that in turn gives us an upper limit on the ...
gandalf61's user avatar
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0 votes

What's the limit on the length of string that can be pulled by a person?

If the string was placed over the ground, friction would become a problem for large distances, when trying to communicate some movement. On the other hand, for a string free in the air, it assumes the ...
Claudio Saspinski's user avatar
4 votes

What's the limit on the length of string that can be pulled by a person?

There are two big practical problems with using string for signalling - it stretches, and it breaks easily. You can replace the string with wires or metal bars - this was the system used for ...
gandalf61's user avatar
  • 50.7k
3 votes

What's the limit on the length of string that can be pulled by a person?

The current set-up faces several issues: The enemy could damage our wire network or there might be some internal fault, similar to the scene at 2:50. Earth's curvature imposes limitations on the ...
Harjot Dhillon's user avatar

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