Hubble's constant

[leifus]

can someone please explain to me what this is? I'm doing my physics hwk

here's the Q:

Use the table to find a value for the Hubble constant.
I have a table full of numbers for various galaxies for the distance (in millions of light years) and velocity of galaxy. There are two figures missing.

I probably shouldn't be asking for help on this but Im sooo confused

[Duke of York]

Try this link

Hubble's law - Wikipedia, the free encyclopedia

From the looks of it you should be able to work out Hubbles Constant pretty easily

Wow I did O and A levels physics and never came across this

[leifus]

Originally Posted by Duke of York

Try this link

Hubble's law - Wikipedia, the free encyclopedia

From the looks of it you should be able to work out Hubbles Constant pretty easily

Wow I did O and A levels physics and never came across this

thanks - I still dont get what the calculation is....

[Duke of York]

From what you have said (and I may have gotten the wrong end of the stick here ) you have been given a velocity v (which I assume if the recessional velocity) and the distance to the galaxy D, therefore from the equation

v = Ho x D

you have v and D therefore you should be able to work out Ho (Hubble's constant) from Ho = v/D

Though I am a bit confused as to why there are 2 figures missing

[leifus]

Originally Posted by Duke of York

From what you have said (and I may have gotten the wrong end of the stick here ) you have been given a velocity v (which I assume if the recessional velocity) and the distance to the galaxy D, therefore from the equation

v = Ho x D

you have v and D therefore you should be able to work out Ho (Hubble's constant) from Ho = v/D

Though I am a bit confused as to why there are 2 figures missing

thanks a lot!!! I think I get it now

[leifus]

here's the Q:



how do you find the missing values?

[pressld2]

So having worked out the hubble constant by using the data given for Virgo, Ursa Major and Corona Borealis you then have to use it to calculate the distance to Hydra and the recessional velocity of Perseus.

So multiply the distance to Perseus by the Hubble constant to get it's velocity and multiply Hydra's velocity by the Hubble constant to get it's distance.

Easy, peasy, lemon squeezy!

Dave P.

[leifus]

Originally Posted by pressld2

So having worked out the hubble constant by using the data given for Virgo, Ursa Major and Corona Borealis you then have to use it to calculate the distance to Hydra and the recessional velocity of Perseus.

So multiply the distance to Perseus by the Hubble constant to get it's velocity and multiply Hydra's velocity by the Hubble constant to get it's distance.

Easy, peasy, lemon squeezy!

Dave P.

so is the h.c different for each galaxy? or is it just one number?

[Duke of York]

Originally Posted by leifus

so is the h.c different for each galaxy? or is it just one number?

I think you'll find if you do v/d where both numbers are present it comes out as the same number

[KeenTeen17]

right. lets get this sorted. to find the constant you need to divide the velocity of the galaxy by the distance

I'll do it for you shall I
1200/72 = 16.66666666666666666666666666667
15000/900 = 16.66666666666666666666666666667

The 16.6.....7 is Hubbles constant its just the simple matter of rearranging the formula.

to find the distance of Hydra just 60000/6.666666666666667= 3600

to find the velocity of Perseus just do 400x16.66666667= 6666.666666...7

if you need any further help just ask!

[Duke of York]

Originally Posted by KeenTeen17

right. lets get this sorted. to find the constant you need to divide the velocity of the galaxy by the distance

I'll do it for you shall I
1200/72 = 16.66666666666666666666666666667
15000/900 = 16.66666666666666666666666666667

The 16.6.....7 is Hubbles constant its just the simple matter of rearranging the formula.

to find the distance of Hydra just 60000/6.666666666666667= 3600

to find the velocity of Perseus just do 400x16.66666667= 6666.666666...7

if you need any further help just ask!

Come on you should at least have given him something to work out rather than doing it for him

[KeenTeen17]

Originally Posted by leifus

so is the h.c different for each galaxy? or is it just one number?

sorry just read the other post. the hubble CONSTANT is the same for all galaxy hence the name constant

[leifus]

cheers, thats my hwk done now i get it