Scientific Notation and Dimensional Analysis

[@ProfessorDaveExplains]

Yikes! At 2:33 I accidentally put a nine at the end of all those zeros instead of a one, what a silly mistake! Also, there should be a zero before the decimal point. I was not as careful and thorough at the beginning of the channel as I am now, please forgive me!

[@morganng3624]

ya, i got confused at first but now I know that you know your mistake. Good Job Mate and keep up the good videos.

[@jr2340]

Wheres my dad,Robert Lusa

[@dbneptune]

Thanks for the notice!

[@ammyvl1]

it's ok it made sure that i was paying attention :^)

[@shivamchouhan5077]

It's OK proffesor sometimes it can happen Thank you prof

[@maxidavis8513]

I just want you to know that I struggled with conversion/dimensional analysis throughout my Chemistry class and Engineering class in high school and this video was that moment where I got it. Thank you!

[@dbneptune]

I’m not watching this series for help in school, you just make it so fun that I want to learn this in my own time! Thanks Dave!

[@levishhunted7593]

that's awesome dude!

[@elizabethlegaspi8283]

Thank you, Professor Dave for creating this page! I'm currently taking CHEM 10 online summer session and your video are extremely helpful. You cut the fluff and get straight to the point, which makes learning the "scary" chem material fun.

[@mohammedkhaledaldraimli4468]

I couldn't agree more... Professor Dave made it short and sharp

[@arziebautista4101]

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[@arziebautista4101]

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[@arziebautista4101]

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[@arziebautista4101]

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[@ciarawalker4980]

Majoring in biochemistry. This fall will be my first semester. Better binge watch + take notes (even though I know most chemistry) the videos were too well done to just skip over!

[@fufu8236]

OHHH MY GURD! I am also starting this semester majoring in bio-chem. INTERNET HIGHFIVE!

[@ciarawalker4980]

HAHA HIGH FIVE

[@Music-nn9mi]

the absolute wonderfully helpful information made me disable my ad blocker

[@philawsophy3197]

Currently studying this chemistry for my medical entrance exam. I am hoping I can finish the GenChem Series so I can proceed to OrgChem. Thank you Professor Dave.

[@Abcdefghijklmnopqrstuvwxyz1024]

2:40 you can do that with any measurement unit you could use parsecs if you wanted

[@davidboygenius6843]

I love your videos! You're almost at a mil! Congratulations and keep making videos!

[@jeanlanz2344]

Thank you for a wonderful video...One point, please...at 2:34.... 10^-9 is shown incorrectly. Thank you for generously sharing your knowledge. God bless.

[@omegaminus2866]

4:19 1.5460000 2.0.00019 3. 8.88x10^9 4. 4.5x10^-9 * 27.78 m/s

[@lightning8542]

I can do complex algebra and trigonometry, but for some reason I struggle with unit conversions. This video helped to fix that. Thank you so much.

[@levishhunted7593]

how do you do trigonometry?

[@Maryamhassan310]

omg you make this so fun, God bless you

[@jermble]

Thanks so much!! I missed the class where we mentioned dimensional analysis and my teacher told me to watch this to get the general idea.

[@TheKids422]

same

[@Metskins_Poker]

Doubt you are still reading these but the conversion from km/hr to m/s only has originally 1 sig fig so shouldn't the resulting answer technically be 1 sig fig? I understand making sure we are doing the math right but I also want to make sure that using sig figs it would actually be 30 m/s

[@johnwilliamj.r9196]

Thank you so much Professor Dave,I never really payed attention in high school and somehow I made it to University to study Geology, now these series are being very very very helpful for me to catch up... thank you thank you...

[@elizevdspuy2]

Thank you Professor for sharing your knowledge and explaining in the needed an relevant information!! Your video's and small hits have helped me understand my work so much better. When my tutors don't know the answer I know you do!!

[@Jtke9112]

At 3:21, why is it 10^9 nm and not 10^-9 nm? I thought nm is equal to 10^-9?

[@ProfessorDaveExplains]

It is, so there are 10^9 of them in one meter.

[@MillionairesDiary]

i graduated highschool years ago but this is an awesome refresher. Feels good to comprehend

[@ChemEICast]

I agree

[@supermanwithabeard03]

I don't understand how you got 27.8m/sec with "Express 100km/hr in m/sec". I'm sorry, Professor Dave. I'm taking my first ever chemistry class (college) this year and I've never been good with math. This is throwing me off. I don't understand it and I'm getting pretty frustrated/discouraged. Where does the 27.8 come from? I know this is simple to you and others, but to me... I just don't understand how you arrived to that. I wish you would have worked it out in the video. I'm terribly confused. I appreciate your work, however, and I thank you for it all. Just really, reaaaally confused on that particular part.

[@ProfessorDaveExplains]

+supermanwithabeard03 once the units cancel out, just do the arithmetic! multiply all the numbers in the numerators, then divide that by all the numbers in the denominators.

[@supermanwithabeard03]

+Professor Dave Explains Still majorly confused, my friend. I'm completely dumbfounded on the arrival of the answer 27.8m/sec. I keep getting 166.6(repeating). The "seconds in a year" example was extremely easy, of course, since you broke it down so well, but I'm scratching my head over this.

[@ProfessorDaveExplains]

it's (100 * 1000) / (60 * 60), just the numbers that are in the fractions.

[@supermanwithabeard03]

+Professor Dave Explains Wow. Well, that explains everything. I don't know why I overcomplicate things. Thanks, Professor Dave. Sorry about being a nuisance. Your videos have helped a lot. Classes started last Monday; I'm just trying to stay a step ahead of the game. I'm signing up for tutoring soon.

[@ProfessorDaveExplains]

not a problem, my friend! everyone learns differently. feel free to email me with questions!

[@TheEmpoleon123456789]

Your intro is fantastic XD

[@beatsbydave32]

My science teacher says that your hair makes you look like Jesus.

[@b.cmagwaza6365]

Oh! My Gosh, lol. Anyway thanks for the good work Dave does.

[@MrNanah38]

If you are brainwashed to accept what Jesus supposedly look like.

[@JurassicJosh341]

no he looks like cisco ramon from flash a little bit

[@justinfeagans6171]

Professor Dave died for your sins.

[@shivamchouhan5077]

I think his hair makes him look like newton.

[@JC-xk8vh]

Best explanation of D.A. I have seen.

[@blurrypigeon]

thank you professor dave

[@MysticdestructionAJ]

THANK YOU. I had no idea how to do this before this video.

[@Starburstluver69]

can someone please explain how to do the comprehension questing where we have to convert the 100/hr to m/secs?

[@thewildrobb]

Okay so you have 100km/hr as a fraction, multiplied by 1000m/hr because there are 1000m in a km. Then you have 1hr/60min multiplied by 1min/60 seconds. You do the cross out thing, all your left with at the top is 100x1000m over 60x60seconds which equals 100,000m/3,600sec Then you divide that fraction by 3,600 because we want 1 sec Then you get 27.777m/sec and you round so it equals 27.8/sec

[@cptray-steam]

Wow I can do dimensional analysis now, previously I sucked at this stuff now I am somewhat decent at it thanks Dave. Now I just have to figure out how to memorize that table you showed that displayed the kilo = 10³ and stuff.

[@syaoransakura8839]

Wow, this video tutorial is just really good. They even had tests in the end. Love it

[@stjonal]

Hello. Awesome channel, I am going to love watching what you make in the future. One thing that bothered be though was your calculation of the number of seconds in a year at 4:07. You seem to have taken into account the significant digits. Under normal circumstances this would be correct, as the numbers with the lowest significant counts are the 60's and 24. However, these are integers with a defined unchangable size. They have no need for greater significance, since by definition there are only 60 seconds in a minute, 60 minutes in an hour and 24 hours in a day respectively. The only one that could be debated is the number of days in a year, since leapyears are a thing, and leapseconds accordingly. In a normal, non-leapyear there are exactly 31536000 seconds. no more, no less. For ease of use its good to give the scientific notation, but it distorts the number of significant digits in the number.

[@TheKids422]

thank you

[@OtabekHoshimov_]

Still I couldn't understand how you expressed km/hour in meter/seconds in comprehension session, if you know it please share your understanding. Thank you!

[@poolmaster18]

Times 100 by 1000 to get it into m/hr, then divide by 3600 (which is 60X60 as there is 60 seconds in a min and 60 mins in an hour) to get the answer in m/s

[@arianalemus2787]

Thank you for helping me out! First video I watched of you and you helped so much! Also, the theme song is everything! LOl🤣🤣

[@salmauthmaan8148]

For the comprehension, the conversion, why did you get 27.8? Since it is multiplication/division, then the answer should have the same sigfigs as one with the fewest. SHouldn't that be 1 Sigfig?

[@dhooth]

Hi, where do the sig figs at 4:10 come from?

[@klowicloe4497]

Help! How did he get the final answer in scientific notation form at 4:09 ??? I'm confused

[@DorianBlackberg]

Great content. Something fundamental seems to escape me. SPOILER FOR THE COMPREHENSION SECTION AHEAD Converting 100k/h into m/sec, i seem to not understand how to convert using the fractional version of 1. Is it arbitrary? Cause I did 100km/h x 100m/km x 60min/1h x 60sec/1min which is a jumbled mess, so my question is how do you decide what is at the bottom and what is at the top? cause both 1h/60min and 60min/1h equal 1

[@cabji]

I want to know this too. How do you decide what goes where? In the lesson he converts time to time, but in the comprehension we need to convert 2 units of measure at the same time. What's the rules for doing this? My best guess is you "repeatedly multiply by an expression until both units of measure are converted to the desired units of measure", then multiply the top and bottom values and divide the results to get the answer. I'm only here because a soda can says "ALL NATURAL COLOURS" and then listed COLOUR 129 in the ingredients and so now I'm doing Professor Dave's Chemistry course BECAUSE I NEED ANSWERS.

[@shahabbaloch8338]

my one question wasnt answered that was when solving for work how do we find cosine of theta? please reply soon im stuck

[@moot5978]

did u get the answer in time?

[@humain1025]

Thanks. This and sigfugs has helped me through physics quite easily.

[@laurencoll7015]

I’m not good at math but I really want to learn physics and modern physics and understand quantum mechanics. Where should I start? Should I start with a math course even if I have to learn like elementary math concepts I’m just not sure where I need to start to be able to understand this stuff ?

[@ProfessorDaveExplains]

Yes, if you want to understand quantum mechanics you need advanced math. My mathematics playlist covers pretty much everything you need, and it starts at elementary school level arithmetic, so start that from the top and work your way through! Then hit the classical physics and modern physics playlists.

[@laurencoll7015]

@@ProfessorDaveExplains oh goodie ! Thanks so much for the guidance and for making these videos in general ! I’m super excited! Thanks again !!

[@cloakingemu7427]

seriously grateful for the videos

[@anush7386]

Give more on dimension analysis plz

[@demigod6860]

your hair is awesome dude

[@ProfessorDaveExplains]

+Zubair H. thanks, friend!

[@anush7386]

+Professor Dave Explains plz ans me

[@Fandomsaremylifee]

I'm watching this legitimately because I don't understand dimensional anaylasis and my teacher hasn't made it much clearer

[@LexyMackailia]

I love the intro already.

[@sophiang1427]

In the last question to convert km/hr to m/sec, why do we not considering the sig figs in this question and use only 1 sig fig in the answer?

[@ProfessorDaveExplains]

ah perhaps i should have put a period after 100 to imply 3 sig figs, at any rate it doesn't matter too much, it's just an exercise for conversions

[@sowmiyafarhath807]

Sir,kindly explain @3.28 how 10^9 nm ÷ 1metre How it could be equal to one? Is 10^-9gm÷ 1metre the right one?

[@ProfessorDaveExplains]

a nanometer is a billionth of a meter, so you need a billion of them to equal a meter.

[@sowmiyafarhath807]

@@ProfessorDaveExplains thank you sir...

[@cecyzero5239]

I'm not sure if you will see this but I had a question about express 100km/hr in m/sec. I was wondering if it is OK to round it at 2.8 m /sec. I saw you left it at 2.78, I just figured the more reduced the better.. But is it left at 3 sig figs because the 100km is 3 sig figs? I guess.

[@thnxm8]

When I hear it in theory it sounds so hard and complicated. When I try it with maths then it gets a lot easier.

[@shaemarcia9026]

I'm totally going to fail my first test

[@frenchlearner19]

Question: why is the symbol for centimeter "c," and not "cm"? Similarly, why is the symbol for millimeter "m," and not "mm"? I thought the symbol "m" represented meter? Thanks a million and I cannot adequately express my immense gratitude for these incredible lectures

[@gabriels2395]

As they say, If you cannot explain it in simple terms, you don't fully understand it. Does anyone know why Prof. Dave used 3 sig figs instead of 1 in the conversion from years to seconds? It makes more sense to me this way, but he said that in multiplication we use the fewest number of sig figs. Why is it different here? Thank you!

[@ProfessorDaveExplains]

oh that was arbitrary, i could have written 1.00 years but it's just about saving space. when doing dimensional analysis with conversion factors sig figs don't apply, 1 day is exactly 24 hours to an infinite number of significant figures just like 1 km is exactly 1000 meters with no uncertainty of any kind.

[@gabriels2395]

Professor Dave Explains thank you!

[@gabriels2395]

Professor Dave, could you tell me please why you did not include all the other digits in the calculation but rather rounded it? i.e 3.15 x10^7 instead of 3.1536 x 10^7 I understand that you deliberately decide what amount of accuracy give in the answer even when there's no uncertainty at all, right?

[@Fjuron]

Damm, this is good to know. Finally, I can read the very big and small numbers my calculator puts out 😁

[@fgnmghdshd6056]

0:40 man, there has to be at least 3 stars there

[@commitfelonyfeline]

4:15 my stupid eyes gazed upon this slide for so long, on the brink of giving up, I just let it play out and to see the answers then I realized they were seperate questions

[@dominicnikon6276]

Do you have any videos showing mole conversions and molar mass?

[@ProfessorDaveExplains]

yep it's just a couple clips later in this general chemistry playlist.

[@reemzebara]

Thank you so much you explain in a very excellent and fun way and you are even better than my teacher !! 💙

[@markvincentordiz]

Will scientific notation result into an inaccuracy of the resultant answer? ..because there are 31,536,000 seconds in a year(not exactly it is but according to your example) but when you transform it into scientific notation, it become 3.15x10^7 which will give 31,500,000. ????????

[@ProfessorDaveExplains]

well any measurement will go by a relevant amount of significant figures, so you don't have to round that way unless a calculation requires it.

[@markvincentordiz]

😱

[@kairu9373]

2:40 is so oddly satisfying to see

[@braylinbroussard1221]

2:45

[@Shmadailys]

i still not understand

[@ebqguy372]

thanks dave very nice video I learn so much.. nice work

[@zooalkings6557]

I have a question how can I convert from cube centimeter to square meter

[@Musicanna09]

This makes sense…. How? How is it that a 5 minute tutorial explains this better than my teachers?

[@TheKids422]

That's because Dave is intellectually gifted, “If you can't explain it simply, you don't understand it well enough.” ~ Albert Einstein

[@nazmulislam9306]

This guy's awesome!!!

[@thatcoffeefeel8]

Wow that canceling method is so easy

[@samuraistan5922]

Wonderful

[@aqibexplorer529]

Yo men you're superb men

[@darthjarjarbinkstherealsit6832]

Fun fact. Nano means Dwarf.

[@SaifGamer-xx3ry]

انا اماراتي وفهمت عندنا امتحان يوم الأربعاء عن هذا الدرس

[@anush7386]

Like what is plank constant dimension

[@ProfessorDaveExplains]

planck's constant is given in joules times seconds!

[@matsuato9415]

what about english to SI

[@NigelWard2008]

You say the distance to the nearest star is 4.1 x10^16 m. I believe the correct figure is 1.496 X 10^11 m. Could it be that you don't consider the sun to be a star?

[@ProfessorDaveExplains]

*besides the sun

[@vivekraj1281]

Hello professor ! i just watched your couple of videos,it really helped me a lot....,professor can you explain about the properties of periodicity ?

[@ProfessorDaveExplains]

i've got a clip on that! check it out.

[@ebqguy372]

by the way just to let you know.. your hair is AWESOME!!!... like bro..:)

[@dillenp036]

ily dave your my chem father

[@utkarshraj3272]

👍👍👍

[@loreta4665]

Huh, it never occurred to me that we base our counting system on 10 because we have 10 fingers.

[@tryhardninja6943]

thank you chemistry jesus

[@jas4788]

I get it, and then I try to do the problems and I forget everything. Anyone have tips?

[@venusa2347]

I still don’t understand how to express km/hr to m/sec

[@Kaleki935]

Teachers never explain. This is exactly what my issue was 10 years ago, how does he know what to put where? I'm saying in my head the "100km in 1 hour", "1000m in 1 km", then when I say "60 seconds in 1 minute", it's somehow wrong and everything is jacked up. It's why I would get wrong answers by doing the correct math and generally explained equations, but get more points for submitting the correct answer sourced from anything except my own mind. School is a joke, taught by clowns.

[@Fluxinate]

Our Jesus

[@brianfleming706]

Hello fellow Mr. Noguchi students from hurricane hilary

[@TonyNguyen-it7vd]

I like these videos, but I feel they're too overly simplified and won't stick in my head.

[@ProfessorDaveExplains]

if they're simple they should stick in your head more!

[@Keylow_Africangummybear]

im confused my calculator says 277.777

[@Keylow_Africangummybear]

my bad didnt punch in an extra not before the multiplying the 60s

[@klumaverik]

Anyone else start singing a milli by lil wayne?

[@markcranston4377]

Okay. I have now accepted, after failing every comprehension so far that I'm not very bright and that's fine. I'll still keep watching anyway because there's pretty colours and you look like Jesus.

[@C4S4N0V4_]

Dave you look like Jesus

[@feejiphilip]

No apologies necessary! Let’s move on.

[@RobertoLion]

The videos are short, I hope the next time you don't add intros and outros for all videos.

[@thomasbalckwellgorges9201]

2:48