Help with Physics homework? Missed first physics class..

graate

Hey everyone..

Missed my first week of school due to being sick and was sent home some homework. Basically the physics work is converting units to SI units and showing it also in decimal form.. answers to be written like so..

20 cm --> 20 x 10^-3 (power of minus 3) 0.20

I'm not quite sure whats going on here... could somebody who knows possible explain to me the process? How do I find the decimal form afterwards?

One of the questions for example... 750 micrograms to kg

Thanks, really appreciate it! Will save me getting in trouble or looking like an idiot.

bren2001

graate wrote: »

Hey everyone..

Missed my first week of school due to being sick and was sent home some homework. Basically the physics work is converting units to SI units and showing it also in decimal form.. answers to be written like so..

20 cm --> 20 x 10^-3 (power of minus 3) 0.20

I'm not quite sure whats going on here... could somebody who knows possible explain to me the process? How do I find the decimal form afterwards?

One of the questions for example... 750 micrograms to kg

Thanks, really appreciate it! Will save me getting in trouble or looking like an idiot.

750 micrograms is 750 x 10^-6
i.e. the answer is .75 *10^-3

graate

bren2001 wrote: »

750 micrograms is 750 x 10^-6
i.e. the answer is .75 *10^-3

Thanks a lot for the help but I'm more looking for the process. I'm still not quite sure what is going on.

bren2001

My answer is actually wrong, didnt notice the micro to kilo.

750 micrograms

micro is 10^-6

i.e. you move each digit back 6 places:

0.000750 grams

But we are dealing with KILO grams i.e. 10^3,

so this has to be moved back another 3 places

0.000000750

to conform with standards the number has to be between 1 and 9

you will notice that this is 7 places behind the decimal point,

7.5 X 10^-7

graate

bren2001 wrote: »

My answer is actually wrong, didnt notice the micro to kilo.

750 micrograms

micro is 10^-6

i.e. you move each digit back 6 places:

0.000750 grams

But we are dealing with KILO grams i.e. 10^3,

so this has to be moved back another 3 places

0.000000750

to conform with standards the number has to be between 1 and 9

you will notice that this is 7 places behind the decimal point,

7.5 X 10^-7

I understand everything but the part in bold...


So 1500 mm to m would be ... 1.500 x 10^-3 is that right?

fizzyorange

If you have log book I remember it having all the SI units in it, so you just look at the figure, look at the word in the question and then find it in the log.

This one is actually quite hard to explain. :L

bren2001

graate wrote: »

I understand everything but the part in bold...


So 1500 mm to m would be ... 1.500 x 10^-3 is that right?

If you understand everything up to the point in bold you have it! The end bit is quite easy.

Pretty much your answer has to be 1 X 10^ or 7 X 10^, it cannot be 47 or 0.7, that number before the 10^ HAS to be between 1 and 9, it cannot be any other number.

Its the same process each time, remove the 10^ and rewrite in the form you want.

fizzyorange wrote: »

If you have log book I remember it having all the SI units in it, so you just look at the figure, look at the word in the question and then find it in the log.

This one is actually quite hard to explain. :L

Aint in the log tables anymore, the blue log tables have been phased out! They are still the only ones I use in college....

Tweej

bren2001 wrote: »

Aint in the log tables anymore, the blue log tables have been phased out! They are still the only ones I use in college....

Tip no. 1 for entering into physics. KNOW THOSE LOG TABLES.

They are in there. As is hundreds upon hundreds of other useful bits of information.

If you want an A1, you will know those tables better than your own mother.

bren2001

Tweej wrote: »

Tip no. 1 for entering into physics. KNOW THOSE LOG TABLES.

They are in there. As is hundreds upon hundreds of other useful bits of information.

If you want an A1, you will know those tables better than your own mother.

Im fairly confident they took them out. The current batch of physics students get the "formula tables" now. It is vitally important to know what formulae are in there along with what constants and where they are.

The blue log tables are gone, long gone, 3 years now. The little table that contained all of the these terms are gone. (I could be wrong, but I flicked through these a few times and have not seen it).

Neodymium

graate wrote: »

to conform with standards the number has to be between 1 and 9

you will notice that this is 7 places behind the decimal point,

7.5 X 10^-7

That means, instead of writing 60 x 10^22 you would write 6 x 10^23 or instead of 67 x 10^-12 you would write 6.7 x 10^-11. It's just a social convention amongst scientists, they are still both correct its just the convention to to have the first number between 1 and 9