Physics has a purpose

[Catbert]

I was bored, so this is how fast a 160 # person is going after dropping a 200 foot cliff. Mind you there is no air resistance, and the initial velocity vertical equals zero.

77.32 miles an hour, or 113.4 feet per second

Time in the air is 3.5 seconds.

Maybe I will learn impact force soon...

[MOHSHSIHd]

I was bored, so this is how fast a 160 # person is going after dropping a 200 foot cliff. Mind you there is no air resistance, and the initial velocity vertical equals zero.

77.32 miles an hour, or 113.4 feet per second

Time in the air is 3.5 seconds.

Maybe I will learn impact force soon...

so if youre on spats thats like 12 seconds of hang time?


sweet...

[AKBckntry]

I was bored, so this is how fast a 160 # person is going after dropping a 200 foot cliff. Mind you there is no air resistance, and the initial velocity vertical equals zero.

77.32 miles an hour, or 113.4 feet per second

Time in the air is 3.5 seconds.

Maybe I will learn impact force soon...

The 160 lb weight is a given for Earth, but normally you'll work physics calculations in terms of mass because mass is constant regardless of the force of gravity, where as weight is a product of gravity's effect on a mass.

Physics was my favorite class in HS. Projectile motion, circular motion, waves. So cool.

[wicked_sick]

I liked physics in highschool because it was nice and quiet and I could sleep and play games on my graphing calculator. I could also drool on my desk while doing either of the aforementioned and no one would notice.

Then in college it got hard all of a sudden and made me drink.

Now I'm finishing up in trade school. Piss on physics. I'll let the laws act on me without complaint or question.

[runethechamp]

Time for you to learn some more physics. If you don't count air resistance, the mass (or weight for that matter) is irrelevant.

[Catbert]

The 160 lb weight is a given for Earth, but normally you'll work physics calculations in terms of mass because mass is constant regardless of the force of gravity, where as weight is a product of gravity's effect on a mass.

Physics was my favorite class in HS. Projectile motion, circular motion, waves. So cool.

I changed the 160 Pounds to 72.6 kg... and rune, lets pretend we are in a vacuum.

[runethechamp]

You didn't understand my comment. In a vacuum, the mass is irrelevant.

[Big Blue]

I changed the 160 Pounds to 72.6 kg... and rune, lets pretend we are in a vacuum.

Time for you to learn some more physics. If you don't count air resistance, the mass (or weight for that matter) is irrelevant.

Umm, what part of irrelevant don't you understand?

[Catbert]

Whoa... How does that work? I am just in intro, not AP or anything.
[Edit]: I am an idiot. It is just accelerating by -9.8, just AT. the mass serves no purpose.

[runethechamp]

speed is acceleration integrated over time. distance is speed integrated over time. That pretty much sums it up.

OK, some more, with improvised symbols:

speed = int(g,0,t) = g*t+constant. Speed=0 at t=0 => constant = 0
distance = int(speed,0,t) = int(g*t,0,t) = 0.5*g*t^2+constant, distance=0 at t=0 => constant = 0
if you know the distance, t=sqrt(2*distance/g) and v = sqrt(2*g*distance)

Time for Ogre to step in I think....

[wicked_sick]

Gravity is a constant force and will act the same on any object on earth. If there is no resistance to counter the force of gravity (ie in a vacuum) you'll fall just as fast as a bigrig or a penny.

in other words, Newtons 2nd law.

[Big Blue]

or you can use kinetics instead of kinematics and say:
1/2 mv^2 = mgh
1/2 v^2 = gh
v^2 = 2gh
v = (2gh)^.5

[mntlion]

where is the orge when you really need him ?




kinda cool really ...

[Ogre]

THIS ENTIRRRRE THRRRRREAD IS

PISSING ME OFF!!!!

GRRRRRRRRRRRRRRR!!!!


nnnNNNNNERRRRRRDDDDS!!!!

POCKET-PRRRRROTECTORRRRRRRS!!!!

GEEKS!!!!

[joshbu]

Terminal velocity calculations here: http://www.tetongravity.com/forums/s...minal+velocity

[Sphinx]

I rewrote Matlab, including state-space manipulations, on my abacus.

I do numerical integrals in my head for fun.

I can stabilize any system, and place poles at will.

I can travel faster than light.

Einstein forgot to include the Theory of Relativity as it Relates to Sphinx.

[TeleAl]

Whoa... How does that work? I am just in intro, not AP or anything.
[Edit]: I am an idiot. It is just accelerating by -9.8, just AT. the mass serves no purpose.

Galileo would agree.
The big stone and the small stone hit the ground at the same time
when dropped from the Tower of Pisa.

Mass or weight play no role.
Density does, but that requires consideration of air resistance.

Now then, a complete understanding of this requires Isaac Newton and his Calculus.

If you have not learned about integrals and derivatives, well, all I can say is,
that's what they are all about. Plus a good many other things.
Absolute genius he was!

[AKBckntry]

Time for you to learn some more physics. If you don't count air resistance, the mass (or weight for that matter) is irrelevant.

Of course, but in elementary physics air resistance is not considered.

We did learn the properties of matter and energy in a vacuum, including the awesome experiment with the buzzer in the vacuum.

I'll bet those Star Wars geeks wouldn't have enjoyed their flicks so much if physics had played a larger role, i.e. the lack of sound in the vacuum of space. Same goes for Star Trek and others.

[AKBckntry]

THIS ENTIRRRRE THRRRRREAD IS

PISSING ME OFF!!!!

GRRRRRRRRRRRRRRR!!!!


nnnNNNNNERRRRRRDDDDS!!!!

POCKET-PRRRRROTECTORRRRRRRS!!!!

GEEKS!!!!

Ogre becomes a nerd in "Nerds in Paradise", does he not?

[TeleAl]

And you should also consider an important question:
Where would you land hucking that cliff with a given velocity?

For this, one can use vectors. Trig might work, but with Calculus. Me need to think this over.
What's your vector Victor? Roger Roger.

[glademaster]

Saying you keep it simple and only calculate the vertical component of said skier's speed, you'd still have to factor air resistence to get a number that is even remotely accurate. There is a massive amount of air resistence on a person over the course of a 200 foot fall, enough to make the numbers change a lot. Also, as it's been said above, in a vaccuum, mass is irrelevant.

Obviously, if you add vectors, things get trickier.

[TeleAl]

Also, as it's been said above, in a vaccuum, mass is irrelevant.

To clarify, mass is irrelevant. Period.

When air resistance applies, it is density, not mass, that matters.
Think of a ping pong ball versus a rock of same size.
Think of a basketball and rock of same mass.
Think density!

[ill-advised strategy]

What if the verticle component of skier's speed prior to takeoff and the air resistance cancel? Is that even possible?

[Shorey]

I need a shit. If I produce a man size two piece with a gratifying release resulting from the injestion of 0.5 tonnes of chinese take away (with prawn toasts) the night before, digestion period 8 hours, at what speed will the shit with a water content of 0.2cm3 per acre, hit the water in the toilet bowl? For a bonus mark - if my education was paid for, should I feel bad that I don't understand what the fuck you are all talking about?

[Shorey]

Too slow.

The correct answer was a dissapointing 1minute 3 seconds. The first fell clean and took less than a second, the next went off course and hit the porcelain. It took the completion of the front page of the sports section before it hit the desired destination. The devation was likely caused by a mega tonne methane explosion at the point of release resulting from the Guiness swilled down with the take away. Either way, the experiment was completed and completed well.

yes..I washed my hands after.