Perfect Elastic Collision / No Final Velocity Given
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- Опубликовано: 17 ноя 2015
- Solving when final velocities are unknown. 50,000 views later on a video made for a Canadian student via youtube request. The complaint I've had over time is the masses that I left in grams... Let me help you, on COM problems like this... It doesn't matter. The units cancel out, so the ratio of the masses are the only things of value, so rejoice that you can leave the numbers in a more palatable condition and still get the answer right. Turdfurg's gift to you.
I'm so glad I found a math channel in my language, I was getting tired of having to translate English to Ainglush.
Responding 2 years late lol.... I'm glad to hear someone thought my southern dialect still qualifies as English :)
Thank you for helping me pass physics! You remind me of the history teacher I had in 7th grade. I miss that guy
Glad I helped. Sounds like you had a pretty special teacher in 7th grade. If we find one teacher that actually cares if we learn or not, then we've done pretty good. The "good ones" always want you to come where they are, so that you may go further. Glad you passed. Now go be amazing!
The only video on this topic that helps me understand how to solve this type of questions! Thank you so much xx
enjoyed watching your vid, I didn't know I could get a laugh from a math video. Thanks and cheers
Thank you. This is so direct and clear.
This was a very informative video, good sir!
Thanks God I have found this ...thank you so much
Thank you so much:). I've been trying to solve this problem for 2 days.
Glad to help :)
Thanks a lot dude! I've understand this than my teacher
What will I do if it ask for the final velocity and mass of ball after bieng hit by a cue ball??
Thank you man! I've been struggling algebraically to solve for v2 and v1 final from conservation of energy equation because it has square root. This equation really solves the problem without going into deep algebraic expressions
I'm just happy to help. Keep Learning!
Great explanation, this is a lot less dry than most other physics explanations, thanks a lot!
frrrrrrr
What if they have the same mass or kg but different velocity?
This helped so much! Thanks! And I love yer accent!
You can take the boy outa Alabama, but you can't take Alabama outa the boy. Thanks for watching!
Thaaaaanks, this was the only problem i didnt get in school. 😄😄😄
You're a lifesaver!!!!
Thanks a lot man! God bless you@ :)
How you found out that the Velocity is m/s while at the same time the mass stayed in grams and not in meters???
Perfect explain ❤
thankyou sir , i understand it very well .
Very helpful, Thank you.
Genuine life saver you are!
in the back ground i'm hearing the eighties song "i need a hero" playing. No joke i'm about to youtube it now lol. glad it helped.
IAn eccentric billionaire CEO has an office on the top floor. He insists on having a personal elevator installed that consists only of a giant spring that spans from the basement to his office when it is uncompressed. If his mass is 120kg, what spring constant in N/m is required so that he momentarily comes to rest on the ground floor?
can you help me out with this problem please
It's been 6 years have you found the answer?
You just made it easy for me.
Thanks a bunch!
lmao this dudes accent
roll tide lol
why didnt this work for my elastic collision problems :C
Very helpful thanks
I had a question
isnt the formula 1÷2×mu square +1÷2.....
because we have this formula in our textbook
Thank you so much for this!!!
you are very welcome :)
Teacher, we have verlocity 1 and verlocity 2 after collision, and have we have Recipe to solve when they stop?
You would have to know the type of friction, but of course, if the friction acts.... the collision is no longer elastic.
Great video
Please help me calculate this
a car of mass m moving at a speed of v1 collides and couples with the back of a truck of mass 2m moving initially in the same direction as the car at a lower v2.
a) what is the vf of the two vehicles after collision?
b) what is the change in kinetic energy of the car_truck system in a collision?
9 Years old and a little long winded, but here it is my friend:
ruclips.net/video/wRcPlK-bspw/видео.html
The example I work the second vehicle has an initial v of zero is the only difference.
how would i know wether there is a lost in the energy or not, would it say in the question that there is no lost of energy
elastic = no loss of energy, inelastic = loss of energy
This helped so much
Thank you!!!
you are welcome :)
God bless you
Thank youuuuuuuuuuu!!
That was amazing
I would settle for better than average, but thank you :)
it help me a lot! especially with that sweet accent
sweet home Alabama lol. thanks :)
why 10 mass become a velocity
Pov u got test tomorrow
in 4 hours fr
just a quick question: if we have exactly the same problem but we do not know mass for each object, can we cancel the mass on each side?
This reply is too late to help, but no no no. Said in the spirit of an upset toddler lol.
@@turdfurg67 In your first example i noticed that m2 is twice as large as m1. Would it not be possible to write it at such, and thereby allowing the masses to cancel out on both sides?
@@illinnear7233 I remember once in college when I found a better solution to a problem and pointed it out to my professor, "You could do it that way mister, but some of us came here to work today".
Seems better to cut down a student than to admit you had a brain fart. Good job :) It would be much much simpler math.
thanks man.
Hey sorry, I dont understand sth… why is there a minus before the 5m/s when the vector already gives the correct direction? Would this not imply the ball going in the opposite direction of the vector direction ?
think of it as a number line. since this is one dimensional the 8 ball is going in the chosen negative direction.
Thanks youuuuu
I also have a question as to why you didn’t convert g to kg? Idk my teacher cuts marks for that😅
you're welcome and your teacher is ice cold. I don't because it makes no difference in the formula. I would argue with my teacher that the dimensional analysis still works, so I should not be deducted. Since the equation is basically mv=mv, then its basically a glorified proportion, so the units come out in the wash (excuse my alabama slang). If I was solving a problem of a Hydrogen nucleus, then I sure would not want to use 1.67 x 10^-27 kg, I would use 1 amu. If it hit helium then m1= 1 amu and m2=4amu. Mean teachers man, stop making physics ugly... That would be a good t-shirt.
There is something I don't get. Both balls go at 8 m/s relative to each other, so why do the individual speeds matter? From the perspective of the red ball, the black ball moves at 8m/s towards it and from the perspective of the black ball, the red ball moves at 8m/s towards it so it should be equivalent to saying that one ball moves a 0m/s and the other moves at 8 m/s?
You've said nothing egregious. I guess 6 years later looking back is I should have explained the reasoning, but I think in other older videos I had done that. The relative velocities are not our concern, but the conservation of momentum, so the initial momentum consisted of +0.030 kgm/s and -0.100 kgm/s. SO the initial momentum of the system is -0.070 kgm/s, which means the final is as well. Focusing on the momentum should have been a focus on the conservation, but a youtuber had just asked me to solve a problem like that, so I kept it as straight forward as I could.
@@turdfurg67 Thanks for answering. I should have specified that the reason I asked this question is because I thought there could be a way to simplify the problem by assuming one ball has an initial speed of 0 and the other has an initial speed of 8 (or -8) but I guess it wouldn't really simplify anything because at the end we would still have to convert the answer because the frame of reference isn't the same? Or it wouldn't work at all because both balls don't have the same mass? I am just curious.
How did he derived the formula V1i+V1f=V2i+V2f?
The cinetic energy conserves. So Ec1 = Ec2 and you will get something like m1(v1i^2 - v1f^2) = m2 (v2f^2-v2i^2), and you divide that with mv1i + mv2i = mv1f + mv2f which is also m1 (v1i - v1f) = m2 (v2f - v2i) and....you will get that :D=
AlbOuse Banana oh, thanks!
thank you!!!!
what if they don't give any velocity?? like they're from rest and have no final
0 initial momentum = 0 final momentum
(v*m = momentum)
Can I ask something? Why did you add 5 each side and where did 5 came from?
Algebra, move the 5 to the other side to make V alone
Excuse me!!! what's Vi+Vf=Ui+Uf come from?
It's derived from conservation of energy. There's another video on my channel where I derive it.
why we didn't consider the "ball no 11" to have the negative velocity?
As in both have negative velocities, but one overtakes the other? The formulas are all the same. All that changes are the values you substitute into the equations.
thank you sir
Just what i needed
Thank you
I needed someone to feed (Was that song reference reply too obscure in 2021?)
Thank u very much 😊
you are toooooo kind :)
How about if one final velocity is missing?
If one final velocity is given then you just need the conservation of momentum equation. plug and chug the answer. Let me know if you're still stuck.
Why did you subtracted-160 from each side of the equation?
just separating it from the variables before final division.
4:33 why negative 5 not positive because kinetic energy does not depend on the direction?
we may have derived the special equation from using KE, but we are working with momentum and must maintain the vector nature. Forgetting (+) and (-) is the number one reason students miss points on these. I would teach you to always use your signs and in the advent of it being a scalar like work or energy, then it would eventually square itself out and become positive through calculations.
I finally understand thx to you!You'll get sponsored if your name wasn't turdgurd. But what do i know im learning from you!
I dont get it.🙂
m1v1+m2v2= m1v'1+m2v'2
Thats because its perfectly elastic so no KE gets lost.
m1v'1= m1v1-m2v2
P=m1v1 -----> minus
P=m2v2
I'd help but I'm 2 months behind checking comments. sorry.
Howdy pardner'
اهه ياراسي
Why haven't u converted the grams to kilograms?
Sorry, I'm late on this one. You can do basic mv + mv problems without conversion because the units cancel out. That being said, if you want to do impulse or energy calculations then you must change everything to kg. It's just a lot of problems are just looking for velocity, so say for example it was a helium nucleus and a hydrogen nucleus colliding, then you could use 4 amu and 1 amu in the mv + mv portion and still come out correct and save you from using their x10^-27 kg actual values.
Your voice reminds me of Red Dead Redemtion 2 character
I can handle that. Someone once said I sounded like Landry Clark from Friday Night Lights.
AAAAAAA MINE KEEPS CANCELING OUT CAUSE THE MASSES ARE EQUAL I JUST GET VF-VF=VI-VI
WHen they have the same mass it's beautiful. You still use the two equations in the video, but when you substitute them together all that happens if you prove the two particle exchange velocities. So if object 1 had a velocity of +2 m/s, then the final velocity of object 2 is +2 m/s. I'd add a picture, but youtube hasn't got there yet :(
@@turdfurg67 could you pls type up the the equations because I think I must be messing up... when I cancel out the masses nothing makes sense anymore to me :(
On multiple choice I can just memorize that they exchange velocities but for free response questions I am screwed
@@tsariza ruclips.net/video/Piw8dO5ENsA/видео.html Just for you. Good luck on free response!
@@turdfurg67 omg I love you 😭
I have lots to learn I see. 😶
Bro, ur final momentum isnt equal to the initial momentum, u are wrong
m1 * v1 + m2 * v2 = m1 * vf1 + m2 * vf2
10 * 3 + 20 * 5 = 10 * 7,7 + 20 * 3
30 + 100 = 77+ 60
130 = 137 ?
You left the signs out of your calculations, which are vital to vector calculations. You also missed a decimal on the 0.3. The difference in momentum sums is 1, and that's because for the sake of instruction I did not keep decimals to thousands place. Thanks for watching and don't forget the directions.
Also on the positive, even if I would have goofed which over 10 years has happened many times, at least there were no irritating adds to watch.
@@turdfurg67 u right, sorry
@@NowisFurther it's all good. Thanks again for watching.
help a lot, thx
emmm yes its yours hhhhhh
thanks?
𝖋𝖔𝖑𝖑𝖔𝖜 𝖋𝖔𝖗 𝖋𝖔𝖑𝖑𝖔𝖜