JoeMK

The Period of orbit of a satellite and its Altitude

 

 

What is the graph for that one?

I heard there's a formula for it.....

i'll give it to u at school

i found the last post a bit difficult to interpret. could u explain it a bit plainer plz.

co-sign!!

LOL

anyone has an idea about the Mass vs distance in circular motion graph?

i really don't know how to connect red shifts and cosmicbackradiation with any predictions of a static universe

Yes' date=' I´m pretty sure. You get an equation for the velocity which (directly taken from your post; didn´t check it) is v = sqrt(G*m1/r). Any change in m2 will not alter the value of v. You can also leave m2 in if it makes you feel better: v = sqrt[(G*m1*m2)/(m2*r)']. Still: Changing m2 doesn´t change v (replace m2 with 5*m2, for instance).

 

The mass cancels out at a much more basic level, actually. The force excerted by a gravitational field g on a mass m is F = mg. Now from Newtonian mechanics, you know that F=ma => a = F/m. Hence, the acceleration of a body caused by a gravitational field is the same for all bodies, regardless of their mass: a = F/m = m*g/m = g.

Two bodies which have the same initial positions and the same initial velocities at a given time and do always experience the same acceleration move exactly the same path. So if your heavier satelite starts at the same height and with the same initial velocity as the lighter one, it will have exactly the same orbit.

 

EDIT: Yes, I know it sounds illogical (unintuitive fits better, here). But it´s also counter-intuitive that a feather falls down as fast as a hammer if there´s no friction due to air resistance.

Thanks buddy

It makes better sense now

It seems illogical that a heavier object needs the same velocity to travel in orbit as a lighter object. I know that gravity acts on all bodies equally, but i'm really having troubles imagining it.

using the formula:

m2*(v^2)/r =G*m1*m2 / (r^2) assuming m2 is the mass of the satellite, it cancels out...

are u sure that means that the mass of the body doesn't affect it's velocity

There is a formula to calculate this

 

F (centripetal) = m2*(v^2)/r (pulls you outwards)

F (gravity) = G*m1*m2 / (r^2) (pulls you earthwards)

 

m1 = earth mass

m2 = spaceship mass (cancels' date=' look the formula, so is independent)

v = spaceship velocity

G = Constant

r = distance to the earth center (radius)

 

So when

 

F(centripetal) = F (gravity)

 

m2*(v^2)/r =G*m1*m2 / (r^2)

 

The force you are receiving is 0.

 

Using this formula you must calculate what speed you need to be in orbit, at that speed forces will cancel out and you will feel weightless and spaceship will keep at the same altitude (will not fall) .

 

If you are using a "wrong" speed, one which does not make forces cancel out, you will start to feel the gravity and you will fall to earth.[/quote']

 

you said that "F (centripetal) = m2*(v^2)/r (pulls you outwards)"

Centripetal force pulls you inwards, then u must mean centrifugal force... however, u put the formula for centripetal, which must be wrong

Are u sure, cuz i don't believe that's right

A static universe' date=' one that is not expanding, cannot dispose of stellar energy. This kind of universe heats up over time [/quote']

 

so what would be ur prediction, if the universe was static would humans die in the near future, or it won't appreciably affect our lives on earth? What about the fate of the universe

We gotta do sum calculations, but i don't think they gotta be that complex. Just a good theory behind a logical explanation

I know that the stars release large amounts of heat as they burn, but the temperature of the universe does not increase, as it is constantly expanding.

If the universe was static, then it'll obviously be much hotter, and most probably we wouldn't be alive.

I need help with the prediction, and as well as to connecting it with the idea of "Red Shifts" and "Cosmic Background Radiation"

Thanks

Imagine that the universe is static and not expanding.

Predict the observations that would be made in regards to:

a. Red shifts in glaxy spectra

b. The temperture of cosmic backgorund radiation

I have attempted to research this, with no luck

i need ideas to get me started

The absorption and re-radiation from solid and liquid objects

We have to design our own comparison experiment, to find out how different substances absorb or reradiate heat(or light). We do not have to do the experiement.

Suggested equipement: A heat or light source, a bar heater or an overhead projector, a heat detector, your choice of solids and liquids.

Any ideas, just need ideas

I'm not really sure what you want for the Force/acceleration graph. Both the force and the acceleration are constant in magnitude' date=' and, with respect to eachother, in direction. That is, the graph of the force vector (ie, the force in a given direction) will be a sine curve. The graph of the accelration vector (similarly) will be a sine curve. The same sine curve. So plotting one against the other just gets a straight line of F vs a (or, more properly, F/m vs a, if you want to take variable masses into account).

 

[img']http://img340.imageshack.us/img340/2544/fmagraph8xu.jpg[/img]

 

If you plot it with F vs a, then all you can find out is the mass, from F = ma. If you plot it as F/m vs a, then all you can find out is that F = ma.

 

"Mass vs Distance" I'm utterly confused about, as it appears to have no meaning at all.

 

 

Unless you mean weight, in which case it'll be a hyperbola.

Mass vs distance is kinda impossibble, cuz u cannot show any time or distance progression. so i agree on the graph

I'm a bit unsure about the force vs acceleration graph however.

I'm sure you can at least get number c' date=' its easy.

As for the chloride question, dont worry, noone came close to getting it right other than phil[/quote']

 

Who are you?

 

More importantly, anyone has any idea about the problem, i don't need the graph just the relationship between the two

Hey,

does anybody know what a Force vs Acceleration graph for an object in circular motion looks like? I've been trying ot figure it out, but couldn't come up with anything

and also

Mass vs Distance for forces due to gravitation

The Period of orbit of a satellite and its Altitude

thanks in advance, much apreciated

no i have been slightly crpytic in the reply

 

silver nitrate is the answer

u serious? How can u

i already handed my assignment up..i used electrolysis

damn good question!

 

one I`de like to know the answer to also

 

 

I suspect' date=' but don`t know, that it`s something to do with the molecules of each metal not being Bonded chemicaly and so are easy to move around with the application of heat, it`s ONLY a guess though!

 

a bit like the difference between Dry sand and Wet sand in the wind, the wet sand has bonding energy (if that makes sense?).[/quote']

 

It's because the impurities disrupt the chrystal lattices of the parent materials.

 

So yeah YT you were basically right.

 

Thanks Guys, much apreciated

Is there a reason as to why an Alloy can have such a different melting point to its composing metals?

this is for high school chemistry, we have just finished studying the moles

would u think electrolysis would be a good idea, as chlorides are soluble in water?

Ok, we got this other question

Use the following information to design the experiment and so complete the questions applicable to it

a. u are given a substance that you know is a soluble chloride (to be refered to as X.Cl.)

b. X is a group 1 cation

Perform a first hand investigation to measure and identify the mass ratios of metal to non metals in a compund and calculate the empirical formula

Anyone got an idea to a procedure? ... i hope i ain't asking to much, thanks

Thanks guys, i think the slow heating and the powder will help me get a better MP

thanks

there's still one question i need help in...i'll make a new thread

i wish we had infrared thermometers. but we're stuck with the standard themometers (300*c). Is there somekind of special technique we can use?The solder is in an evaporating basin, we're using a bunsen burner in a smoke cupboard. I know the melting point should be around 180, but we can't get that exact point when it melts, and there's gotta be some kind of technique to use.

hey, just need some help here

this for some school assignment. We made our own Solder by melting tin and lead in the correct ratio. Now we need to remelt the Solder to find its melting point. Look i now this might sound stupid, but what is the most accurate method of findng the melting point.

this is very impotant, there are 2 questions about it that pop-up in this in this assignment:

1> Suggest a suitable technique and sound experimental practise that should be used so the reasonably low melting point can be accurately measured and confirmed

2> What changes did you make to the procedure in this experiment in an attempt to gain more accurate results. (It is very unlikely but possible that you used the correct procedure for finding the melting point of Solder)

Ok i know these might sound like very simple questions, but that teacher wants us to synthesise on a very high level of thinking, so the answerers ain't quite as obvious as they may seem ...any help srongly apreciated