HI! I am new to this forums and this is my first post. Look, I have a homework problem that I hope you guys know how to figure it out.

 

Here it is:

 

 

Recently, Dr, Frank has suggested that EArth may be pelted by thousands of house-sized comets. When Frank first considered the idea of mini-comets falling to earh , he no doubt tried to make a quick calculation. Comets are like dirty snowballs that evaporate when they enter the atmosphere. Oceans have accumulated from these comets over the years. Use the following information to estimate what percent of Earth's oceans could be accounted for givena constant bombardment by comets over the last 4 million years:

 

 

1 year=365.25 days

1 ton=2000 lbs

1 pound = 454 grams

Density of water = 1g/ml

 

15000 minicomets hit earth every day

Earth's oceans occupy 1.36 billion km3

1 mini comet = 30 tons

 

Help is greatly appreciated, thanks

whats wrong with you doing your own homework you will never learn how to understand it if you dont do it yourself

i dont have foggiest!

 

how would you go about working that out?

 

it is probably some long winded thing which will only result in a theoretically possible approx answer, not a certain one.

 

soz, cant help!

anyway its easy to work it out i have got half of it in the last 5 or so minutes you should listen in class then you would understand it, this may sound a bit mean but trust me listen in class and if you dont understand it ask a teacher

Look, I already tried it and I DO listen in class, the problem is that we never really see how to solve problems like this. This problem in particular is an extra credit one.

Just tell me if the answer is .044 %

and if you really do care 99% of teachers are very pleased to talk to and help students at the end of their lessons [assuming that they have some free time] and also assuming that you did listen in class.

 

i would at least help the guy if i could knew how.... re-looking at the data, i can begin to see how i would start it....

working out how much water each comet makes using

1 mini comet = 30 tons

1 ton=2000 lbs

1 pound = 454 grams

Density of water = 1g/ml

15000 minicomets hit earth every day

and so on like that, but really, this is your homework not mine, just work out how much each comet is, then multiply it by the amount of commets that hit the earth a day, multiplied by days in a year, multiplied by 4 million - or something like that

 

i havent done this, so soz, i dont know what the answer is.

OI you lot, have a stop it!, it was a genuine question, treat the guy with some respect! you`de expect the same treatment yourselves. now play nice!

i tell you what i'll give you how much one comet add's to the ocean its 27240000ml or 27240 litters thats all im telling you

also this question is a load of crap i hate questions like this you couldnt know how much water came of one anyway because most of it would get burnt up in the atomsphere

tell him how it worked out, and give hypothetical examples, let him work out the rest for himself, THAT`s fair, give him the tools, then let him do the job!

 

sound fair?

yub yub YT!

 

1 mini comet = 30 tons

1 ton=2000 lbs

1 pound = 454 grams

Density of water = 1g/ml

15000 minicomets hit earth every day

1 year=365.25 days

you want 4 million years

and finally: Earth's oceans occupy 1.36 billion km3

 

thats the order you want it in, you just need to do some calculations, can you see the thought process?

Ok, I already have that comets alltogether add 5.969646 e 20 ml in the 4 million years. So to find the percent I should divide this quantity by 1.36 billion km3 (what earth's oceans occupy. But how do I convert ml to km3 in order to perform the calculation

Is 1.36 billion 1360000000

Yes.

1,360,000,000.

so as I said before, is the answer 0.044%

 

yes or no? just tell me please to do it again if I have it wrong

 

Thanks

Without working it out, .044% might be about right for 4 million years.

 

Why? Well the earth is about 4 Billion years old, or 1000 times the 4 million years stated in the problem. If we stretch the 4 million by a factor of 1000, this takes us to 44%. IF IF IF all the water on earth came from this source then we are short by 56%, same order of magnitude. Extrapolating present data by a factor of 1000 is a chancy thing, but I would expect that the accretion rate was greater in earth's earlier times than it is now.

 

It ain't the things you don't know that get you into trouble, It's the things you know that ain't so.

1 gram of water = 1 ml = 1 cm^3