2-dimensional momentum problem | Impacts and linear momentum | Physics

2-dimensional momentum problem | Impacts and linear momentum | Physics | Khan Academy

Рет қаралды 607,235

16 жыл бұрын

Courses on Khan Academy are always 100% free. Start practicing-and saving your progress-now: www.khanacademy.org/science/p...
An example of conservation of momentum in two dimensions. Created by Sal Khan.
Watch the next lesson: www.khanacademy.org/science/p...
Missed the previous lesson? www.khanacademy.org/science/p...
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to Khan Academy’s Physics channel: / channel
Subscribe to Khan Academy: kzfaq.info_...

Пікірлер: 109

@d.anielb4661 4 жыл бұрын

the quality is so high i can almost see the numbers I love 2008 youtube

@Ecdubs. 11 жыл бұрын

imagine a world without right angled triangles

@user-fq6bw7lc2v 4 жыл бұрын

and that world will become the one without vector components and other tricky questions like this one

@shambhav9534 3 жыл бұрын

Ohhhh... God, I can't imagine life and geometry with no sin, cos and tan.

@mikasaackerman8682 2 жыл бұрын

A world without right angled triangles won’t be right

@darkmagiciangirl8525 7 жыл бұрын

when u go real deep in the video and forget what youre even trying to solve for

@Spottswoode 8 жыл бұрын

thanks a million, if only my professor could explain in such a fashion

@clairelin4126 3 жыл бұрын

Prof? I’m learning this in gr 12 rn 😭😭

@johnkim96 11 жыл бұрын

7:30. Since Pay + Pby = 0, isn't Pby supposed to be -10, not 10?

@victorcislari6881 7 жыл бұрын

John Kim yeah

@blakewhittle6612 6 жыл бұрын

Watch the video, he realises and states this.

@nelsvletav9818 4 жыл бұрын

Yes he stated it

@drago_thedragonbreaker 5 жыл бұрын

Wait wait wait wait. Isn't PBy supposed to be -10?

@oonbrandon460 5 жыл бұрын

is the same because momentum is a vector quantity,i think he assume downwards is positive

@Phagocytosis 12 жыл бұрын

Actually, there's already classes where they give these videos as homework, and then use the classes to have the students solve problems (especially also those from Khan Academy), supervised by the teachers :)

@jmart2234 12 жыл бұрын

thank you for this tutorial! I understand now. It all makes sense.

@michaelajadedesousa3473 8 жыл бұрын

Thanks. You have such a difference before exams.

@mtado4933 Жыл бұрын

The velocity of B in the y direction should be negative, IE Down, When you subtracted 10 from both sides you didn’t keep the mines.

@19993khk 11 жыл бұрын

Very simple and clear, thank you

@boreycheng9260 8 жыл бұрын

thanks I have learned much more😊

@Habe111 5 жыл бұрын

You are a life saver, thank you so much Sal

@aldcaptain 13 жыл бұрын

thanks a bunch sir!

@cerebral2975 9 жыл бұрын

What if you don't know the velocity of either vector after the collision? How do you solve for that if you were given the initial vector and it's magnitude.

@poisonedcheeseproductions 5 жыл бұрын

i think the magnitude IS the velocity... no?

@poisonedcheeseproductions 5 жыл бұрын

@@leonashley9330 thanks! Well explained!

@CanoManuelGonzaga 3 жыл бұрын

To compute for the velocity of ball B, solve first for its displacement angle: Tan θ = opposite/adjacent. This means: Tan θ = y velocity / x velocity, which will give you Tan θ = -2/2.5, which will give you a value of -38 degrees. The negative value of the angle means it's 38 degress SOUTH eastward. With the angle on hand, you can now solve for the B's hypotenuse using SOH or CAH.

@wizwazzle29 13 жыл бұрын

@Dundertaker yes agreed!!

@workinehmulisa5140 2 жыл бұрын

Thank you khan academy 😘💙❤

@gabrielarpio 13 жыл бұрын

definitely learned more here than in college

@samzeeqable 12 жыл бұрын

you saved my life!!!!

@yangyeshuai3686 9 жыл бұрын

Nice video

@starrish 14 жыл бұрын

You are hilarious ! I love your random weirdness...makes physics more fun.

@aze254 12 жыл бұрын

they should just play these videon in class, they are really good

@anilfogat549 6 жыл бұрын

nice

@tizamusic6168 4 жыл бұрын

If anyone needs the answer for the final velocity of B it should be 3.23m/s.

@TonyqTNT 3 жыл бұрын

Is a boxer applying Force to a target mass with structural momentum or kinetic energy?

@randumbtimes3 14 жыл бұрын

@Dundertaker 1/2 kx^2 k = spring constant x = dinstance from compressed

@ANTBLE989 14 жыл бұрын

Yah ..tnx ..I know.

@SCORPiOASC 6 жыл бұрын

what if we need to find the final velocities of both A and B given only angles for each?

@laviare6214 6 жыл бұрын

How does the momentum of ball A in y-direction + momentum of ball B in y-direction equals to zero?

@Heyheyhey876 4 жыл бұрын

Because they have equal to the Momentum in the y-direction in the beginning, which is called Piy in the video

@onlyAerik 14 жыл бұрын

IF you want a fun read about pool (9-ball) that warps physics just enough to be fun to think about, I recommend the manga "break shot."

@mutakamulenga2289 8 жыл бұрын

cool

@ANTBLE989 14 жыл бұрын

why is P(By) not in negative value ...I mean it is important to have direction in the velocity ..it will affect the other values right ..|???

@11Winfield 13 жыл бұрын

@vandepu93 mate listen 2 video he says exactly that at the start! total inttial velocity equal total final velocity

@AzulaOTP 6 жыл бұрын

How are you supposed to do this if you aren't given the masses or final velocities? I got Va1 = 5.0 m/s. It goes 30 degrees up after collision. B goes -45 degrees down. B starts at rest. How do I solve this?

@rkusuma6852 Жыл бұрын

I think you can just ignore the mass of the two objects

@NerdmasterChang 14 жыл бұрын

Right now I am working on a momentum problem very similar to this one, only you do not know the final velocity of A, but you do know that it is an elastic collision and so kinetic energy is conserved. I have been working on it for an hour and I haven't been able to find the solution. If anyone could offer any advice it would be greatly appreciated.

@danyumassicofficialchannel1061 Жыл бұрын

Did you solve it yet

@pvncher 13 жыл бұрын

@Dundertaker elastic= energy is conserved inelastic= energy in not conserved

@nytsegai 13 жыл бұрын

Can we use the same process if the mass were the same?

@beardededdie284 6 жыл бұрын

The mass of the balls :3 ... I'm sorry that but that got me xD

@AmirMullick 11 жыл бұрын

He said 10 in the down direction so thats like saying -10, but generally you are right, yes.

@xlwaiyiplx 15 жыл бұрын

how did it go?

@LadyLissethify 12 жыл бұрын

no your not the only one watching this more then once

@TheCrappyaccount 13 жыл бұрын

@nytsegai of course you can

@kizzanixon 7 жыл бұрын

lower case p = momentum, upper case P = Power

@violinrocks 14 жыл бұрын

@ANTBLE989 That was a mistake. He fixed it at 8:26

@aze254 12 жыл бұрын

well, they could act like they acctually teach (like some do right now lol) and then show the video as an "eaxample" students will be happy its a video and they'll understand it aswell :p

@futurestig17 8 жыл бұрын

No predetermining velocity

@jasonwei4545 6 жыл бұрын

In what grade do we learn this

@donkeykongboy66 12 жыл бұрын

wouldnt the momentum in the y direction for B be -10????

@futurestig17 8 жыл бұрын

Could you write a little more legible please

@davidchen5463 7 жыл бұрын

8 years ago, 240p was pretty much max resolution at a decent bitrate. And back then, tablets weren't really that responsive since you're writing over a plastic surface instead of glass so naturally, his handwriting isn't going to be the best

@hakimahmad55555 13 жыл бұрын

now i can win the pool's tournament, thnx sal :D

@m1dnightshadow 15 жыл бұрын

this will help me on my exam tmrw LOL

@yapper1200 14 жыл бұрын

thank you so much. you made way more sense than my teacher. lifesaver.

@ml4dj0 12 жыл бұрын

he corrected it after

@Dundertaker 14 жыл бұрын

Could you maybe explain elastic and non-elastic collisions for future videos?

@Dundertaker 13 жыл бұрын

@rabyl123 You're a year too late, I already aced that class :) (thanks to KhanAcademy, of course)

@CanoManuelGonzaga 3 жыл бұрын

Why not use decimals rather than surds? I think the velocity of B on the y-direction should be a negative because it's a vector quantity, and it makes more sense to multiply that by its mass which will give a -10 kgm/s, so when you add ball A and B's momentum on the y-direction, it would add up to zero.

@CanoManuelGonzaga 3 жыл бұрын

Ok, so I was commenting at 8:10. lol

@ndubamunansangu2875 6 жыл бұрын

How do i determine if it is elastic or not?

@drago_thedragonbreaker 5 жыл бұрын

If linear momentum is conserved, it's elastic I think

@subita7835 4 жыл бұрын

@@drago_thedragonbreaker no it's if Kinetic Energy is conserved. Momentum is always conserved

@hajlan91 12 жыл бұрын

i have a test in momentum in 2 h wish me luck

@navintamilchelvam5761 5 жыл бұрын

Superman

@bubbles02010 10 жыл бұрын

after a while, all i see and hear is a bunch of colorful symbols on a black background... *sigh* will i do well in this class?? T_T i'm so screwed~

@aqsamustafabutt5400 7 жыл бұрын

if a body has momentum of 2kgmpersec then what does it mean???????

@ayeshasami3884 7 жыл бұрын

momentum is mass into velocity . mass : kg and velocity : ms^-1

@reck1ess77 14 жыл бұрын

YAYYYYYYYYYYYYYY

@ThePrincessSelena 13 жыл бұрын

soh cah toa should be in blood red :D

@hunterzhang9489 6 жыл бұрын

can Sal please get rid of these low resolution videos?

@beanbaggy1 12 жыл бұрын

ahhhh i dont understand!!

@olivejuice1985 7 жыл бұрын

what is Bobbi doing here??

@ahmadsabateen2223 6 жыл бұрын

How can I use this if it's wasn't for balls but for polygons ???

@fajitaboys 11 жыл бұрын

I found this video to be sub par.

@docters12 8 жыл бұрын

how would you do this without a calculator, mccats don't let you use one

@THUNGUNS 8 жыл бұрын

remember your special triangles.

@docters12 8 жыл бұрын

But how do you get approximations for like square root of 7 and square root of 3s quickly without calculators. Or if u have and angle of 36. I don't want to draw it with a protractor or use mcclair series :(

@THUNGUNS 8 жыл бұрын

+wc3champ wc3chNP cant help you.... sorry. No calculator for momentum problems is crazy

@docmbc323 14 жыл бұрын

he never used calculus, it was all trig

@chickdude75 12 жыл бұрын

midterm in 16 hours, and dear god I would have given up if it were not for you

@YT-cn4yf 3 жыл бұрын

8 years later. We're in the same spot lol. how'd you do?

@chickdude75 3 жыл бұрын

@@YT-cn4yf I managed to squeak by lol. I wish you all the luck and may Sal guide your pencil

@hunterzhang9489 6 жыл бұрын

stop rushing would be better

@donkeykongboy66 12 жыл бұрын

lol nvm

@TeKNiQ50 12 жыл бұрын

But then the profs wouldn't have a job. :)

@MohamedGamal-rv3cm 9 жыл бұрын

just advice , watch this DrPhysicsA

@jilwanrahimi8987 9 жыл бұрын

Mohamed Gamal your other comments says 'talking too much instead of solving, boring', no disrespect to DrPhysicsA but he speaks about the concept and derives formulas rather than 'just solving'.