Physics problem
 

If you traveled to Pluto accelerating at 1 gravitational pull and then at the halfway point started deccelerating at 1 gravitational pull would you ever approach the speed of light?

Yes, the moment you accelerate you're approaching the speed of light.



You're still quite far from it, but you're approaching it :D


How close do you want to be to the speed of light? 1%? 10%? 95%?

yes but it would hurt like a sonofabooch...

if you put a straw from earth to outer space, will it suck out all the oxygen?

The answer is no, you're no where near the speed of light.

g accel (approx)= 10m/s/s; c= 300,000,000m/s. It would take 30,000,000 seconds to reach the speed of light, or about 347 days.

Pluto ranges from 4,400,000,000,000m to 7,300,000,000,000m from us, so lets say 6,000billion meters avg., so we would have 3,000 billion meters in which to accelerate before we had to begin to shut down. Or 30 million seconds, whichever comes first.

It's been way too long since I did algebra and calculus, but we need now to figure out how long it would take to reach 3,000 billion meters at a constant acceleration of 10m/s/s. If it is less than 30 million seconds you have achieved warp speed.

I think.

Easy peasy...

Half distance to Pluto = 20AU= 2991960000000m
1g ~ 10m/sec^2

If we use speed/distance/acceleration formula and start with 0 speed...
http://upload.wikimedia.org/math/6/d...0196d8219a.png

...it boils down to 0.02c for 1g across 20AU. (v=27848088km/h. Speed of light is 1080000000km/h) . Not even enough to experience relativistic effects.


Can I get my friday beer now? :D

You have two equations that must be be solved:
d=1/2 a * t^2
v=a * t

Take the first one:
d=3,670,052,070 miles total, we want half of that, or 1,835,026,035 miles
a=32 ft/sec^2 which is 0.00606 mile/sec^2
From that, you can get the travel time to the halfway point at constant acceleration of G.

Then, you use the same value for "a" and the derived value for "t" to solve for "v", which will be your velocity at that point.

The distance measurements are the average Sun/Pluto distance. If you want the actual Earth/Pluto distance, you have to state a date, since they vary between 38.5 and 40.5 AU.

I had to look it up... it was driving me crazy. d= .5 *g * t^2 (like Mike says)

The distance we are allowed to accelerate is roughly 6,000 billion meters. .5g = 5m/s/s
Therefore t^2 = 1200 billion sec^2, square root = 1,095,445 secs.

Thus, it would take approx. 1.1 million secs to travel 1/2 way to Pluto at a constant g acceleration. 1.1 million seconds at 10m/s/s = terminal velocity of 11million m/s... far below the speed of light at 300million m/s.
(Remember earlier that we had calculated that it would take approx 30 million secs to reach the speed of light at g accel. We ran out of dragstrip here before we had to shutdown)

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Corect answer... 3.66%. Your first guess was pretty good!

Everyone has forgotten a basic. The starting point is not at zero. We are moving thru space as a system, and here on Earth, some additional orbital mechanics are invovled. What would be the real starting point? Relatively and relativity speaking?

Pluto's orbit is also slightly inclined (relative) to ours as I remember. Does this affect the flight path and accel?

Makes the healthcare debate seem trivial doesn't it. One commonality tho.

Lots of zeros in both answers.

Damn I gave you guys an hour and ya already got it. Cool. So now I can write all that out and go get the bonus from my calc teacher. He said he didn't care how we came up with it even if it involved buying someone a 12 pack.

fingpilot... I think theassumption is that you'd travel point A to B in a straight line, and initial velocity from earth would be zero.

Calcuating gravity effects and orbital trajectories is not something you cover in high school physics.

Hey I am not High school. And this was a problem proposed for extra credit in my college calc class.

Tell your teacher there is no calculus involved, you want a harder problem please.

http://forums.pelicanparts.com/uploa...1253298206.jpg

Boobs... thats the answer...

The speeds you are getting to are relativistic. You can not solve this with classical mechanics. If the instruction is to solve this with classical mechanics, follow the path above. Otherwise you can answer this very quickly: You can not reach light speed in a space ship, as the relativistic mass increases with speed and your acceleration required to further increase velocity is going to be approaching infinity.

George

Why would you want to go to Pluto when you can go to Uranus?

Closer to 2.5% of C when you sit and crank the numbers.

Then where did that "1/2" come from in d=1/2at^2??? Calculus rears it's ugly head again!!

No where near relativistic. The Lorenz Factor at that velocity is 0.99679. Therefore, the velocity is in the order of that far off...about 1 mile per second off.

You can't achieve the speed of light and here is why - in very simple terms in order to move, something has to get pushed or thrown in relation to something else. Going from a steady state to a moving state - a continuous change in the position of a body relative to a reference point, as measured by a particular observer in a particular frame of reference - a physical movement or change in position or place.

In order to sustain movement a constant change relationship has to be continuously established between a static against the dynamic. As speed increases the dynamic touches more static thus chnaging position at a greater frequency. This is achieved when the static is non-flexible but as the incidence of relationship between the static and the dynamic increases them properties of both change as well.

Remember, the dynamic and the static of made up of particles that are moving almost at a speed C (the speed of light). As dynamic closes in on C the particles do not have the same physical attributes at lower speeds in fact they no longer act like particles at all but rather a fog of sorts that move via peaks and troughs. Think of a falling chunk of silly putty. It behaves like a solid. If thrown at low speeds upon impact it would feel like a solid but at high velocities, s high speed photo releveals that it actually looks like a liquid and infact it beaves like one as well. Matter is like that as well.

Now, dynamic is cruz'n through and it has movement source (rocket, wheel, EM rail, et al). That movement source is made up of the same stuff its just being re-arranged physically by giving off electrons or bigger - regardless these are still 'things' moving near to the sppeed of light C. What ever is reacting, as speed increases it begins to behave very differently, more flexibility which requires even more energy to go faster. At some point there just is enough energy to help the dynamic displace and change position.

Moving at the speed of light would mean that the dynamic would essentially dissolve into the statics it is trying to displace.

Speed of light...impossible to do so for the dynamic.

Since I have no desire ever to go to Pluto I simply don't care how fast we are going to get there (unless there is a buffet there). Secondly anything more then 100 mph on the ground or 500 mph in the air is simply toooo fast to be of any practical use to me. The Concord is out of service.

Since I can't spell simple words what would make anyone think I can do math...btw WHAT is calculus? Sounds Greek to me.

I truly am amazed at the HP some of you BOYZ have under the hood. I knew I wasn't talking to dummys. What also amazes me is the human condition, so many with HP under the hood and still fumbling around it the dark when it comes to your inner selves and relationships to the world.

There simply is more than the quanatative world, the physical universe. One day I imagine physics will start to delve into the unseen universe that occupies the space around us. We may call that further dimensions beyond the 4 that we physically occupy. I also imagine that our portal to that unseen universe is accessed through our imaginations. If you have any doubts just take a look at how and when Einstein came up with his Theory of Relativity.

Yes- tell you teacher we, PPOT, want a harder problem. Work him over- ask that, if we can solve it and explain it to you enough that you can in turn explain it with confidence to him, that you can get bonus points.

Worth a shot.

I'm breaking out my partial differential equations book right now. We need to get some collective PPOT gears rolling here...

Dudes!

The exact answer is 0,0257c (I assumed 1g = 10m/sek^2 and half distance to Pluto to be 20AE). It's already solved in 8:th post. You don't need to solve two equations, there is already a shortened equation. If you know start speed, end speed and distance then acceleration can be presented this way:

http://upload.wikimedia.org/math/6/d...0196d8219a.png

As we already know the acceleration to be 1g = 9.78m/sek^2 and that start speed v0 = 0 then it's simply a matter of calculating v.

v[m/sek]= sqr(a[m/sek^2]*2s[m])


v being so low compared to speed of light, relativistic aspects don't come into play. As pazuzu said before, Lorenz Factor is almost 1 so it's not worth crunching it from relativistic point of view. Now give as a real problem! ;)

Its been longer than I care to admit since I've taken quantum mechanics but from what I remember, in layman's terms, an object becomes more and more massive as it approaches the speed of light. Thus, it would require an infinite amount of energy to actually attain the speed of light. When an object gets close to the speed of light you have to throw out classical Newtonian physics and start using quantum mechanics, like the Lorentz transform. Typical high school problem, they don't give enough info. I'm an electrical engineer and have taken bunches of advanced physics and calculus classes and every once in a while I can't figure out how to do some of the goofy problems my teenagers come home with. Teachers don't give enough info or give the proper assumptions to know how to get the answer the teacher wants to see.

Now, you could warp space in front of the spacecraft, making an intense gravitational field in front of the spaceship, which would cause the ship to be constantly sucked foreword. This is why the Star Ship Enterprise" has its warp engines positioned so far away from the hull of the ship (so that the whole ship can fit into the warped space).

I try to not hand absolutely everything out on a silver platter when someone obviously wants us to do his homework for him...


A better view is that an objects potential energy increases, so it requires more kinetic energy to accelerate said object. When working in relativity, we tend to get away from the concept of "mass" and convert everything into energy, to simplify the various equations.

You've got it all wrong! You want to go to Her Anus!

+1 you can never go wrong with boobs! :D

She came from planet claire.

I'm missing something here. In this equation does 's' represent time, in seconds? 'Cause it seems we have two unknowns to solve in that equation: terminal 'V' and 'S'. The instructor has given us a distance, a starting velocity (assumed to be 0) and a rate of acceleration. We have to solve whether V=c when that distance approaches, but we would first need to know the value of 'S' for this equation. What am I missing?

What a goofy question.

http://forums.pelicanparts.com/uploa...1253326245.jpg

Just because you're talking about physiscs and gravitational pull why do we have to assume you're talking about a planet?

I actually think Pazuzu's original answer is correct.

is it possible to exceed the speed of light?

Nope :D

bummer

Kind of. Light pulses and sound pulses have broken the light barrier.

http://physicsworld.com/cws/article/news/3630

http://www.msnbc.msn.com/id/16599496/

three times the speed of light isn't kinda

The "kind of" was referring to the fact that it does not beak the law of physics. What do I know, I just Googled :D.

Every single FKNG time I approach the speed of light I approach infinite mass and I FKNG HATE IT!! :mad:

I guess the question is not if it is possible but rather why would you want to?

nope, "s" is "stretch" (It's a "swedish" equation, "s" means "sträcka")...you use it when you know starting velocity, ending velocity and distance.

As you already know acceleration "a", starting velocity "v0" and distance "s" you need to break out "v".