Cumulative General Science/Technology Quiz

[xienwolf]

Nah, I told people to look at this example for more fun than the one they were doing, but I don't think anyone actually discussed it, so I felt it was safe Besides, asking you what arc of your vision is occupied by a star you are traveling toward when moving at 3/4 the speed of light would require too much calculation IMO, but was my preferred question.

And yes, brighteyes is correct. The person in the train sees the tunnel as being Mass Contracted (thus shorter than the train) and the observer outside the train sees the train contracted (thus shorter than the tunnel).

And I think the standard way of stating it is that the second observer is inside the tunnel, but outside the train. So sue me

 

[Brighteye]

What's the normal arterial pressure in the lungs (value or range is fine)?
I'd prefer mmHg, not KPa.

 

[SS-18 ICBM]

I'd say 80-100 mmHg.

 

[Brighteye]

Nope: that's more like a systemic pressure.

 

[Genocidicbunny]

Is it something like 10-20 mmHg or am I going off the wrong end here?

 

[StarWorms]

*thinks back to A level biology*

Well the pressure increases in capillaries (I think...) so I'll have a stab at 500mmHg.

Wait no... that makes no sense! It must be lower... erm... 5mmHg?

 

[Brighteye]

stickciv has it. 12-16 is the textbook range, although he's closer to the mark with 10-20. I had meant to specify systolic pressure, but since I didn't mean pressure will do.

 

[Bartleby]

Sorry to be hijacking, but...
Does that mean you can pump something down to 10mm by sucking on it?

 

[ainwood]

Sorry to be hijacking, but...
Does that mean you can pump something down to 10mm by sucking on it?

Pumping of liquids is limited by the vapour pressure of whatever you're pumping. A vacuum pump can be used to reduce the pressure lower than the vapour pressure.

 

[Genocidicbunny]

Anyone that wants it can go ahead and ask

 

[philippe]

ok:

explain!

 

[dutchfire]

Since speed is relative, the speed at which you're travelling is rather subjective, and as such it isn't dangerous. Acceleration (it should be m * dv/dt though) is what kills you.

 

[Brighteye]

I think the point is that the speed probably won't do you in, no matter how much you accelerate in a normal fall, but the collision in which that speed changes rapidly and converts into a large force on you will kill you.

 

[brennan]

Acceleration to high velocity (falling) doesn't kill you.

Being subject to a very sudden acceleration kills you (hitting the ground).

 

[SS-18 ICBM]

Your speed doesn't kill you, deceleration upon impact does. That's why a cushion will save you.

 

[philippe]

brennan wins this one

 

[brennan]

While standing on a sensitive set of scales, you place your finger in a jug of water that stands on a desk next to you. What happens to the reading on the scales? And why?

 

[dutchfire]

It will seem that your lighter because of the upward pressure by the water in the jug?

 

[Mise]

It'd read you as being lighter, for the same reason that if you put one finger on the scale and the rest of your body in a jug of water, the scales'd show you being lighter. Part of your mass (the part that's displacing the water) is being supported by the water, not the scales. You could look at it in terms of Forces (reaction, etc) if you were that way inclined, I guess. I cba though

 

[xienwolf]

I dunno, if it is JUST your finger then you are going to have to consider the surface tension pulling on your finger as well as any liquid which your body might absorb. Are you dehydrated at the time? If so you could actually gain more weight osmotically than you displace via bouyant forces I suppose.