Kinematics Part 1: Horizontal Motion

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you helped me in math, then in chemistry, then Organic chemistry, and now in physics

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He knows a lot about science and stuff.

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@@johnrubensaragi4125 'professor Dave explains'

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Literally me too

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I just wanted to take the time to genuinely thank you sincerely. For the past 2 weeks in my physics class I have been extremely lost, and your video helped me apprehend the necessary conceptions. Thank you so much.

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You helped me pass genetics and O. chem the second time around. Now here I am drowning in physics and I find out you teach that too... BLESS YOU PROFESSOR DAVE :')

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Got my first ever physics midterm on Monday and things are DEFINITELY starting to click better after watching these videos. Thank you!!

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Why is professor Dave better than the professors I pay thousands for per semester?

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You can always toss a buck my way on Patreon if you're feeling generous! :)

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Does Patreon allow one time contributions, or is it strictly subscription based?

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after acing the chemistry test a while ago, time to finish up the finals with physics, thanks a lot for helping me Jesus!

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...nailed it...ok ill go

[@pyxl2032]

this is like the first time ive ever really commented on anything, but you have helped relieve so much stress about not being able to understand whats happening In my class. Thank you a ton, seriously.

[@oz8232]

Astonished with your unbelievable teaching skills, I never understood its concept in my whole life till I came across this video, what a time and life savor, thanks man, much appreciated!

[@nickvanderwater1088]

You, prof leonard, and the organic chemistry tutor are in the stem hall of fame

[@user-fl4hn5cq7b]

Wow. I can't believe I learned more in this one video than my physics teacher has even tried explaining in the whole term. I wrote a few pages of notes from this and I finally understand instead of feeling overwhelmed and stupid. I really wish more teachers could explain subjects like this, it seems so much easier now.

[@jdorsett4157]

ik this is pretty late but what i did is I rearranged the equation to get "a" (acceleration) by itself. Which is (vf^2 - vi^2)/2d. All i did from here was plug in the values which we know are [vf=0] cuz it skids to a stop, [vi=15] cuz that's our initial velocity before the skid, [d=50] cuz that's the total displacement traveled during the skid, then with a trusty calculator it comes out to -2.25m/s^2. If you're confused on why it's negative it's because it's going in the opposite direction of the velocity, thus slowing the bike down until a full stop! 🛑

[@vincent_mma]

Me pfff physics is boring and hard. . Professor dave - hold my apple

[@graydiation]

... and watch this!

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You explain things so well. I listen to inclass lectures and read the book, but learn the most from watching your videos. I watched for biology and organic chem, and did well in both classes. Now on to physics. Thanks professor Dave!

[@fortimusprime]

ABSOLUTELY MIND-BLOWN! (I mean that in the best way.) Something from an entire chapter that I just couldn't comprehend you explained it in less than 7 minutes! You are a talented person with a gift in teaching! Thanks for your help! You just got a new subscriber! God bless you!

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I'm relying on you, professor Dave. I've been struggling so hard with this the past few days... Let's see if you save my quiz tomorrow, or hopefully my test next week!

[@preciouskarlamalolesloares2609]

Why is Prof. Dave so good at explaining these difficult and intricate topics? I am doing advance readings and this video I mean youtuber, helps me in doing it😂😀keep up prof. Dave!

[@Psiredem]

I may be way too mathematically illiterate to grasp everything in this video, but at least you have helped me figuring out a few things about physics and basic algebra with this single video. Thank you, Professor Dave!

[@freedomofmusic2112]

Your videos are incredibly helpful and well explained. I love how you color the things you are explaining. Your videos have helped me in Calculus & now Physics. This year I got hired as a math tutor at my college, I recommend your videos to students all the time & sometimes I watch them with students I'm helping because you explain things so much clearer & more concise than I can. Thanks Professor Dave!

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i’m so cooked

[@isminivermekistemeyenmahmut]

You can't compete with me at being cooked

[@Lip836]

All you need to knows are the 3 ecuations (third one is actually derived from the other 2)

[@peachysunflower6033]

Who knew Jesus would also be saving my Science Test

[@romacoma6069]

I love how he talks about the history of physics which shows there’s many discoveries/discrepancies in modern science physics at that point of time.

[@NikonAgpas-z2q]

For the last word problem, I used d=(Vi+Vf/2)t to solve for the time. Then, I calculated the acceleration since I already have Vi, Vf and time. I arrived on the same answer which is a=-2.25 m/s^2. :)

[@DJPastaYaY]

Thank you Professor Dave Explains

[@DNSMLT]

If only your videos were around 30 years ago. It's a little late for me now but Im still going to follow. Thank you!!

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Right now taking STEM classes and can't understand some topics but with the help of you I passed all my exams❤❤❤much appreciated and thankyou very much.. PROFESSOR DAVE🎉🎉🎉

[@ThatAerospaceEningeer]

Bro, what hasn't this guy done a video on? He's getting me through my engineering degree.

[@tanjeeschuan4999]

There's also a method where you plot a graph with the x axis being time and y axis being velocity, the area of the polygon in the graph is the displacement of the time, velocity and acceleration of the problem.

[@buenafedomingo7449]

nothing would ever explain how happy I am right now, thanks prof

[@anthonyJrrocks1]

literally the only reason im passing my biomechanics course thank you dave

[@harunosakura9798]

Sorry i have a question in 4:03 pls someone explains me, im not good at english for sure so forgive me 'bout my grammar. Now i want to ask. I thought that the acceleration was 2.5m/s^2 so each second the point would probably move a distance equal to its instantaneous velocity. Let take an example: in the first second, the velocity became from 0 to 2.5m/s because of the acceleration so the distance which the point had ride must be 2.5m. The next second ( about 1s ) the velocity continiously changed its instantaneous velocity from 2.5m/s to 5m/s so propably the distance the point had ride were also equal to its instantaneous velocity at that time and its equal to 5m. So all of the distance which the point had ride = 2,5 + 5 = 7,5m. But if we use the principle in this video, the distance will be: 1/2at^2 =1/2 x 2,5 × 2^2 = 6,25m. So if we follow this principle, the point will ride a distance = 6,25m, but like i've talked about, the distance must be 7,5m. I definitely thinking about it and i dont know what exactly the true question, so i ask and hope that somebody will answer me. Thank all of you, first. Oh, oh so im talking about uniform variable motion so the displacement probably = the distance the point had ride in Ox Tks for reading, and pls help my by answering this ques. Have a good day !

[@farahimad4432]

I'm actually amazed that a young man like him is a professor. Keep it up!

[@ProfessorDaveExplains]

i'm just a youtube personality! but i work super hard so thank you :)

[@yanceca2]

I am so thankful for you! I was getting so frustrated and now I feel hopeful. Thank you for breaking things down in a simple manner!!

[@bhabiknath5739]

hiii cara whats your age? U are so beautiful

[@meezi_moo]

thank you SOOO much for making this. I've been struggling with kinematics really badly in class, and this explained it in such an easy and understandable way

[@abinayasivasamy4708]

Professor Dave, could you please explain about the motion of system of particles and rigid body.

[@egregiouslytalented2381]

super bro.i am 11 years old trying to learn calculus and this kinematics.I HAVE BEEN SELECTED BY MY STATE GOVERNMENT FOR AN EDUCATION PROGRAMME FOR THE BLESSED,SO I HAVE TO LEARN EVERYTHING EARLY.U HAVE HELPED ME A LOT .THANKQ BRO.I CANT UNDERSTAND HOW TO THANK U

[@palesasimelane4322]

I have been reading on this topic in my textbook.Did not understand anything.I understood this in the duration of the video.Thanks Prof

[@halofornoobs93]

This video just helped me catch up in my Mechanics class. I've been so lost until now. Thanks!

[@kevinphilip1957]

Professor Dave really coming in clutch before the exam, thank god for you.

[@stefanandrioskarsson3092]

how did you get 43 at 5:20? i put 1/2(-8.4^2)(3.2)^2 in the calculator and i get -361.26

[@lightbulb129]

I think it's because you put the exponent to the -8.4 instead of the m/s the thing is, you put the whole expression (?) into the calculator except for the units, but the squared (^2) is supposed to just be for the m/s, but you left the exponent there after removing the m/s even though you're meant to also remove the exponent (^2) after removing the m/s itself, which in turn, squared the -8.4 instead.

[@Ricardo-ck7zd]

​@@lightbulb129 i didn't understand what you just wrote, pretend im a 5 yo child please

[@Ricardo-ck7zd]

i figured it out, you are putting -8.2² and it's just -8.2 the ² on ms doesn't count because it's just there to represent acceleration

[@stefanandrioskarsson3092]

@@Ricardo-ck7zd Thanks my man!

[@johnguillen68]

wow, this was a great video. So basically we have to find out first what we have and what we need to find out in order to know which equation we have to use? The first day of Physics was so confusing and now that we're on the 3 chapter (Freefalling​) we have an exam on the first 3 chapters but I still feel somewhat lost. I'm gonna have to watch videos and apply it to what I'm reading to get a better understanding.

[@everardomezajr3495]

How did your class go? I'm in the same situation. Right now, after first class covering ch 1-2 my head is swimming

[@beans7622]

@@everardomezajr3495 aye yo im in the same situation rn 😭

[@chidinmaebere3560]

@@beans7622 SAME I have a test tmr and I’m so confused

[@beans7622]

Chidinma Ebere I ended up just cheating the entire semester and got pretty decent marks lmao. Good luck tho!!

[@chidinmaebere3560]

@@beans7622 thanksss

[@sanzi2291]

My teacher couldn’t explain a thing! He just talks for himself, thank you for saving me from failing mechanical science!

[@o5-1-formerlycalvinlucien60]

for anyone wondering how the kinematic equations are derived, here is what i think is the solution (i'm not that good at calculus, but i think this gives the general idea.) starting with the basics, velocity is the derivative of position, or v = dx/dt and acceleration is the derivative of velocity, a = dv/dt solving for v just involves integration, dv/dt = a dv = a dt v = at + C1 (C1 i think here is the initial velocity) solving for position is just integration again, but using the previous equation dx/dt = at + v(i) dx = at + v(i) dt x = (at^2)/2 + vt + C2 (and C2 here initial position.) solving for the final equation: Δx = (v + v(i))/2 * t = d solve the first kinematic equation for time: v = at + v(i) v - v(i) = at (v - v(i))/a = t Δx = (v + v(i))/2 * (v - v(i))/a Δx = (v^2 - v(i)^2)/2a 2aΔx = v^2 - v(i)^2 v^2 = 2aΔx + v(i)^2 v^2 = 2ad + v(i)^2

[@iunne1113]

Thank you Jesus for blessing me with this video.

[@jarodscott-gonzalez9717]

im a new physics student & i been struggling w grasping the whole concept. thank you so much for helping me with such vital yet easy information!

[@galacticalliance4801]

i think this single video provided me with exactly what i was looking for to calculate suicide burn altitude in kerbal space program, and for that i thank you

[@finlaymma]

at 5:06 you use vf = vi + at but there's another equation t=vf-vi/a which gives the same answer just wondering if they're the same and I can use them in the same scenarios, anyone know?

[@Jxrdan_07]

I used the same thing before I found the answer, I’m guessing you can use multiple things but yeah idk

[@jorgeluisvilelavelarde5689]

Hello, I have this question. I have data of horses. vertical acceleration. If these values are registered by ms and I have -0.4, 1.2, 3.1 and -0.08 m/s2. How can I get a measure of each horse? may I take just the average? or Should I do another calculation? Thanks a lot for your help.

[@faisaldlg735]

tbh your the only person that i go to if i need help in anything my guy your AMAZING LIKE REALLY Thank you professor Dave i would spend money for you and congrats 1M

[@kokku10-b77]

I love your intro Ur intro can be a good meme

[@lupinsensei]

Dave: …some simple equations… Me: my brains on fire 😂 In all seriousness though, thank you. I’m determined to wrap my head around all of this.

[@isazisempi3896]

Ill never understand why in academia we skip so many steps in explanations. if you wrote down the formula x=x0+vi(t)+1/2a(t)^2 and then saw him use x=vi(t)+1/2a(t)^2 you would be confused until you realized they took out the xo lol. the question never gave a distance therefore I guess you can set it to zero. For somebody who never studied instantaneous velocity or physics they would wonder how the car had velocity an no displacement. failure in communication is the biggest setback in science and engineering.

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If all the stored digital information was suddenly lost, we can rely on Professor dave as a back up drive for all of the world's information.

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I love science.Your videos are great Professor.

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i love professor dave u helpped me very much with my FY04 voima JA liike

[@arthurfoster8919]

I don't understand why at 5:25 it's x = 86 - 43 Where does the 43 come from? 0.5(-8.4)(3.2) gives me -13.44. Thanks and I appreciate your videos.

[@ProfessorDaveExplains]

you forgot to square 3.2!

[@loren5693]

You helped me a lot professor and my physics exam is near so wish me luck!

[@elizabethjeno-2082]

There were more than one equation to solve distance , how do we know which one is the best to use when solving questions?

[@ProfessorDaveExplains]

You just have to see which variables you have defined. Choose the equation where you can plug everything in except distance so you can solve for it.

[@Baniii1001]

i was hoping i could learn physics from you too since your chemistry videos were amazing and im so glad u do teach physics as well!!

[@horizonbrave1533]

Hey Proffy Dave, I have a question...When I am getting more into physics I see a lot of talk about "Deriving an equation"...or something like "Derive the kinematic equations" etc... Is this the same meaning as literally taking the derivative of the equation? Or does "deriving" in this sense mean something else? From what i see...when someone says they "Derive an equation" it doesn't seem like the same idea as taking the derivative of a function or equation? How are they releated/different?

[@ProfessorDaveExplains]

Oh no no, it has nothing to do with derivatives! It just means to formulate or generate the equation, like someone had to first develop the equation, and we can use existing equations and plug things in and manipulate them algebraically to get new equations, so that's what that means.

[@nickpetrowski7182]

How did you get to (-225 m2/s2)/[2(50m)] Where do the numbers come from and how do you know to divide?

[@Mike_Wazowskii7]

at 5:55 How are getting from 0=-255+2a(50) to -255/100=a (with the a isolation) I got the same answer but it took longer to do. I tried first dividing both sides by A but that didn't work so well. Then tried dividing both sides by 2a and got a bizarre answer at the end (2812.5).

[@ProfessorDaveExplains]

subtract 255 first, then dividing by 2 and then 50 is the same as dividing by 100. just regular arithmetic! remember we are solving for a so we want to get that by itself.

[@Mike_Wazowskii7]

Wow, thanks a ton. I was going about it backwards lol I like your series by the way. Good job on them

[@edot9631]

Thank you Professor Dave I’m feeling a lot more hopeful about Physics 1

[@razexal1450]

*Can someone help me. I'm confused on* 5:55 *how did he get -225? If it's 15^2 why did it become negative? I need answers ASAP hehe. Thanks!*

[@betseloteyob3199]

Because he shifted the number to the other side

[@kuchisabishi.]

When you multiply with negatives doesnt it make a positve?

[@Comrade4213]

Could explain to me where did you get these kinematics equations from.

[@juanorozco973]

Thanks so much i have a test tommorow and i finally understand this

[@ahmadalfalasi7490]

YOUR THE BEST MAN

[@meloncraft514]

It’s crazy how I can actually understand the equations in your videos since you’re good at explanations, but I still can’t figure out why you would 1/2at^2.

[@elliejohnson2786]

Thank you for showing the working at the end! I followed along and just... Didn't really know how to get the correct units, I wasn't paying attention to how the squared velocity applies the squared aspect to the units as well.

[@mehrinisoqoshboqova]

I really want to watch your videos ☺️

[@tairod7212]

6:03 why the heck is it minus -225

[@technicalamit4519]

Cuz the acceleration is negative

[@jkgaming0565]

This actually helped a good bit and I have a test tomorrow. Thanks!

[@kaye4525]

Thankyou for this,the video link that send with our teacher is i didn't get it,but when i saw your vid i just know itttt thankyou so much

[@missmaggie5509]

OMG...professor Dave is truly saving my a$$. Thank you for breaking everything down!!!!

[@deutschnacharabischemgeschmack]

Thanks alot for your effort. Are you planning on making such a play list for Engineering? That could really help. Thanks alot

[@ProfessorDaveExplains]

Yes I am!

[@haihaiiro]

I just want to thank you Professor Dave, it is really hard to study especially this subject, Physics during this challenging time (Pandemic) combined with the Online Schooling. You act as a bulb that lights our mind thanks! You made it simple but effective.

[@theodoresweger4948]

I never noticed before, but the wheels are not turning. Very well explained thanks so much

[@arleighjanpangatungan953]

Hi Sir I have been puzzled on how to solve this problem are you willing to help me? Question 1. A 35 g bullet was fired horizontally from a gun with a velocity of 320.0 m/s. If the barrel is 1.1 meter from the ground, how long will it take for the bullet to reach the ground? Question 2. A 35 g bullet was fired horizontally from a gun with a velocity of 315.0 m/s. If the barrel is 1.5 meter from the ground, how far will the bullet reach as it first hit the ground? Thank you so much

[@johndo3164]

I was wondering if my answer is correct by accident. I got the same answer but I used other formulas. Vf=Vi+(a*t) and Xf=Xi+(Vi*t)+(0,5*a*t^2). I used the first formula to write a in terms of t so: 0=15+(a*t) -> a=-15/t substitute in second formula: 50=0+15*t+(0,5*-(15/t)*t^2) solve for t gives t=50/7,5=6,67 seconds. Substitute back in first formula: 0=15+(a*6,67) solve for a: a=-15/6,67=-2,25 m/s^2.

[@applefan8819]

when you hear “he knows a lot about the science stuff, professor dave explains” you know u have a test tomorrow 😂

[@lavenderlillymi]

Im struggling so much in class my teacher said to quit physics and drop put of school Ill prove her wrong Ill make her clap for me one day Thankyou so much for helping me out i can understand better

[@divinebrandconsults217]

PLEASE SOLVE THIS A coin is pushed from the edge of a laboratory bench with a horizontal velocity of 15m/s of the height of the bench is from the floor is 1.5m. calculate the distance from the foot of the bench of the point of impact with the floor. (g = 10m/s2)

[@divinebrandconsults217]

I ALSO NEED EXPLANATIONS PLEASE

[@sho16Gaming]

This was a really informative video thanks Professor Dave

[@allichiru5525]

He knows lot about science and stuff professor Dave explains

[@jamesvincentaves4339]

Thank you Physics Jesus

[@wilsontadala2327]

Hello *I have a math problem* A gry is an old English measure for length, defined as 1/10 of a line ,where line is another old English measure for length, defined as 1/12 inch .a common measure for length in the publishing business is a point define as 1/72 inch . what is an area of 0.50 gry² in point square .

[@daniellep5168]

this might b a dumb question where did the equation at 3:51 come from? Can somebody explain

[@daniellep5168]

what's confusing me is where the Xo came from.

[@carultch]

@@daniellep5168 It comes from calculus. Start with a given that acceleration a is constant. Definition of acceleration: a = dv/dt Solve for dv: dv = a*dt Integrate: int dv = int a dt v = a*t + C C is an arbitrary constant, as is routine with integration. Note that at t=0, we want v to equal v0 by definition. Thus C = v0, and our equation becomes: v = a*t + v0 Now look at the definition of velocity: v = dx/dt Substitute: dx/dt = a*t + v0 Solve for dx: dx = (a*t + v0) dt Integrate: x = integral (a*t + v0) dt Integrating a*t gives us 1/2*a*t^2. Increase the exponent, and put the reciprocal of the new exponent as the leading constant. Think about the area of a triangle with base t, and height a*t. The area is 1/2*a*t^2. Integral v0 dt is just v0*t We get: x = 1/2*a*t^2 + v0*t + C Another arbitrary constant of integration. This one we know needs to be x0, because we want the initial position to be the number we call x0, when t=0. Thus: x = 1/2*a*t^2 + v0*t + x0

[@anjellypalaspas5534]

saw the intro and already clicked subscribe

[@ahmadalfalasi7490]

BEST PROFESSER

[@dontdisturbme6330]

yery good video but can you give derivation of equations of motion

[@ProfessorDaveExplains]

i thought that might be a little too much algebra for this series, but i'll put it on the list for another one!

[@ayushijain8671]

Hello..I really liked your video of graphical analysis...Understood it really well and I am quite clear about it. Can you please make a video explaining velocity distance graph or give me tips or steps to understand such graphs... Thank you very much :-)

[@ProfessorDaveExplains]

buddy i did that already! go through the classical physics playlist.

[@ayushijain8671]

I mean velocity vs distance graphs

[@Theodorus5]

Guys he can't do everything for you

[@charmielcharway9301]

You are the best 👍👍 Thank you so much Sir Dave.

[@benjaminmauleon5149]

Why does the initial velocity has a negative sign on 6:01??

[@ProfessorDaveExplains]

it doesn't, it's 15

[@pumpkinshardx7242]

Thank you math jesus

[@mollyb5275]

My question is after you are done with these and rounding to appropriate sig figs, do you use the 2 used as part of the formula or only the measurements in the equation to calculate how many sig figs should be in your answer? My teacher is confusing me on that part.

[@ZENZU28]

Hi I am teacher frank and your videos help me a lot specially in physics

[@kuromimi_112]

thank u so much i've been looking for these more complex formulas for an hour. glad u have them

[@MechE_Emma]

If given the answer for the latter problem, is it able to be said that it would take the person 22.2 seconds to stop fully?

[@Kevessi]

I dont get it. If the car is moving ONLY horizonta3, arent you supposed to only use the horizontal component formulas? And therefore not using the vertical(free fall) compinents

[@ProfessorDaveExplains]

those equations do not specify a direction, they can be used for vertical or horizontal all the same.

[@Kevessi]

@@ProfessorDaveExplains OMG THANK YOU VERY. But then again how do you know WHRN to use the four kinetic formulas instead of the component formulas

[@ProfessorDaveExplains]

i'm not sure what you mean, you just look at the variables you have and the one you want and choose the equation that fits your needs.

[@Kevessi]

@@ProfessorDaveExplains im mean like the question says that the car is moving horizontally then they ask the velocity. The velocity horizontally has a different formula from the one vertically. So i was confused when you used the vertical formula of the velocity to find the velocity. Im talking about horizontal projectil type of shit

[@ProfessorDaveExplains]

as i said, there is no such thing as a "vertical formula" or "horizontal formula". these equations are not specific to a direction. the same equations are used whether the motion is vertical, horizontal, or at some angle.

[@badao8277]

Hi, i found your video in 2021, kinda like it, i'm studying in something that called dynamic, do you have some thing like that. It would be a big help if your video can help me understand what i am doing at the university. Thank you, from vietnam

[@ProfessorDaveExplains]

Most of my classical physics playlist is kinematics and dynamics, watch the whole thing!

[@ZombieBowTiie]

Thanks for creating a free resource for learning. And also, whoever did your greenscreen work, fucking props to the dude/dudette