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Science: Everything explained by PV=nRT, F=ma=Gm(1)•m(2)/r^2

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Theophite (good follow on Twitter) pointed out the biggest issue is that basically plutonium is the only material energy-dense enough to make these things viable for anything Michael Bay or James Cameron would be interested in.
 
I keep reading this. I keep almost getting it.

What started me down this path is my age-old problem with "force." Specially, with the difference between F = ma and p = mv.

Let's think about what happens when you are in a car at a stoplight and a car rear-ends you. What is the "jolt" you feel? Is it F? Is it p? Is this a difference between an evaluation of the forces in the entire system against the viewpoint of just one component of that system (my car getting rear-ended)?

My first intuition is that the car hits me and applies a "force" on my car. But then I look at that equation, F=ma. What if the car is decelerating when it hits me? It's in the process of going from 50 mph to 30 mph but it hits me going 40 mph. That can't mean what it says, that the force that hits me is negative.

OK, so, maybe it only matters that I suddenly start accelerating to 40 mph from being at rest. That jibes with my intuition that had I been moving 35 mph when the car hit me going 40, the actual forces imparted to my car would have been much less (as my additional acceleration is just 5 mph).

Does any of this make sense? If any of you teach physics in high school I am sure you can explain this to me in a way I can grasp in seconds.
 
Kepler said:
I keep reading this. I keep almost getting it.

What started me down this path is my age-old problem with "force." Specially, with the difference between F = ma and p = mv.

Let's think about what happens when you are in a car at a stoplight and a car rear-ends you. What is the "jolt" you feel? Is it F? Is it p? Is this a difference between an evaluation of the forces in the entire system against the viewpoint of just one component of that system (my car getting rear-ended)?

My first intuition is that the car hits me and applies a "force" on my car. But then I look at that equation, F=ma. What if the car is decelerating when it hits me? It's in the process of going from 50 mph to 30 mph but it hits me going 40 mph. That can't mean what it says, that the force that hits me is negative.

OK, so, maybe it only matters that I suddenly start accelerating to 40 mph from being at rest. That jibes with my intuition that had I been moving 35 mph when the car hit me going 40, the actual forces imparted to my car would have been much less (as my additional acceleration is just 5 mph).

Does any of this make sense? If any of you teach physics in high school I am sure you can explain this to me in a way I can grasp in seconds.
Click to expand...

At a high school physics level meaning we're ignoring friction, wind resistance, and other outside forces...

Each action which involves overcoming inertia requires a force.

in the case of deceleration, F=ma is measuring the force being applied by the brakes.

In the case of the collision, F=ma is measuring the force of the car impacting your car. It also means a=F/m. Your car will accelerate in proportion to the force being applied to it by the other car at the point of impact.
 
Really what you are feeling is the transfer of energy from the first car hitting you. While it's energy dropped a lot from 50 to 40 (on the way to 30) before it hit you, the transfer of energy was an increase in force to that car over the brakes. The transfer of energy takes time- and over that time, there's a different F=ma- all of which, you feel. And some of the energy is taken by the deformation of the body of the car (thankfully), otherwise, a quick acceleration like that to your body would be very damaging.
 
Slap Shot said:
Isn't it nearly impossible to have less than 100 anywhere in the U.S.? I'd be lucky to see 50+ here...
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Its easy to have less than 100 in Maine. Heck I just got cable 2 or 3 years ago. I was lucky to have 10 before that. Some towns that have some money have done gigabit fiber in more populated areas in town. Elons Satellites may make hard to have less than 100 in a few years as long as you don't have houses or trees blocking your view of them
 
aparch said:
But 25mbps is just fine per the FCC....
Click to expand...

Per person for basic stuff? Sure.

Tack on video conferencing and you'll need a full MB/s/person;
engineering-sized files (medium is usually 10MB-100 MB, large are 100 MB - 10 GB) require 100 Mbps to start. 1 GB @ 100 Mbps = 13 minutes.
1080p is somewhere around 1-2 MB/s (Blu-ray from discs is closer to 5 MB/s). 4k at 25 Mbps seems... dubious. That's essentially 3 MB/s. Don't buy it for a second.


The FCC is just so effing backwards.
 
Fireflies in long exposure:

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I'm going to give a shout out to the people way before me who helped us figure out which mushrooms added flavor, which ones could kill you, and which ones would make you see God for a week.
 
This is very strange. It doesn't make any sense unless you see it really, really large, and also maybe spin through some of the videos out there about the macro structure of the universe.
 
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