I missed a day of my hs ap physics course that explained a way how to get both final velocities after a collision like this and I couldn't get help on it and there is a test later today. This video just saved my grade. Thank you so much

I love you videos, they have helped me a lot in my school, in fact this video helped me proved a test question was worded wrong.

Thank you so much. You teach so much better than my actual university teacher who fails to make me understand anything. you're the reason I'm hopefully going to do good in my physics mid-term, thanks.

I hate physics and you don't make me love it; but you DO make it easier to learn. Thanks!

This is the sort of whiteboard you'd look at and cry because it's literally just a foreign language of alien symbols. Yet it makes perfect sense now, in 11 minutes, after reading 30 pages of blabbing in my course book. Brilliant and thank you from the UK.

Stumbled upon this video purely by accident, and I just so happen to have a problem which is exactly the same to this with different numbers. Thank you for explaining it. I understood it perfectly.

Professor van Biezen, I'm sure all of us have who have watched your videos can agree on one thing: You are a life-saver! I just want to say how much I appreciate but it just truly won't fit in a comment.

and i didnt get the multiply by 2 of final y velocity part either, where did the 1 went when we multiply 0.5 with 2?

These problem presentations are great: very clear!

Thanks, this was a great help to me for my class. When I play pool, I do not have to go through all of this, though!!!

this is how physics should be taught, thank you.

Your videos are always helpful I love you so much I even recommended your videos to my friends Thank you!!!

Hmm, for a perfectly elastic collision, theta1 + theta2 should add to 90 degrees. So the fact that they don't in this example means that the collision is not perfectly elastic and therefore kinetic energy is not being conserved (kinetic energy will have been converted to deformation heat, noise or friction). Would have been interesting to calculate this loss in kinetic energy.

Great explanation! I will be watching more of your videos.

Took me a month to solve but I finally got it thanks to your help.

Thanks so much! I will subscribe. This helped so much (:

Nice question! I have physics summative today and it somehow helps

Do you have a video where you do this problem using vector diagrams?

Yukelele The angle after collision, depends on the angle of impact, not on the size of the balls.

ABSOLUTE BANGER MATE, NEVER SEEN ANYTHING BETTER 73/10 WOULD BANG AGAIN XX Love your sweetheart

I'm making a game and I have a problem. What if I know velocities (whose are implemented by a code) and masses so I have also initial momentums and I want to calculate velocities and angles both particles at the end of the collision. I found it difficult because of insufficient number of known variables. How can I achieve it?

amazing video, the explanation was great.

Amazing lesson, and a big help for preparing my own. Thank you!

Made things clear thank you

Thanks a lot. Couldn't find this problem ( going in angles) in any of the books

thank you sooo much, you've saved my life

Great video, very helpful!

you're a great teacher

Thanks a lot. I was confused with that negative sign.

THANK YOU VERY MUCH SIRR. I,m a bit confused that why did we choose upward final velocity of sin30 with m1 in y direction and sin45 downward with m2? how can we judge to join the appropriate sin ? will m1 always go upwards? thanks for the video though it really helped alot. Reply me in your free time :)

Great video, thank you so much!

so helpful! thanks

Thank you so much, this was so helpful :)

Very clear and concise.

if the two masses are the same, shouldn't the angle between them be 90 degrees instead of 75 degrees?

very clear explanation . thank you so much ..

Thank you so much for this.

Had the same question with different numbers on my homework. You saved me man

Thanks, this helped me so much! Was very stuck.

Subscribed and didn’t look back thank you 😊

Is the total angle between the particles' velocity vectors after the collision supposed to be 90 degrees or can they be different angles?

i dont know if anyone will answer but on the left side when he puts a value for cos of 45 degrees he puts 0.707 however cos (45 radians ) is 0.525

The title must be corrected to inelastic collision because the problem and its solution in this video are all about momentum conservation. In elastic collision, the conservation of momentum and kinetic energy must apply. The professor did not take into account kinetic energy conservation.

Great Sir. Thank You

sir can you please make a video solving for a question regarding an ornament breaking into three pieces and take three different paths

thank you so much. saved me

Great vid. watched several. HOWEVER, Would love to of seen a video of a combo of linear momentum and angular momentum together in a collision in such that a pool ball is moving at a given velocity; WITH a rotation of a given rad/sec backspin, colliding with another ball. Using alpha, and w(omega) in angles while using the P momentum system. I been assigned several of these in my classes this semester and can't find videos. Thx and keep up the great vids.

What will happen if you have 3 unknown? Final velocities and the one of the angles.

Sooooooooooooooooooooooooooo awesome! Thanks!

At Piy=Pfy about @7:12 Why did you plug on the sum of upward and downward? It shoud be upward- downward, isn't it? Because it is a momentum which always calculates about the sign of direction. I am so confused right now.

How would you be able to find the angles prior if they were initially unknown?

Once I have encountered the quiet similar task: an elastic collision of two fixed pairs of balls. I haven't managed to solve it. A sad story.

thanks.. it help me a lot..

Thank you so much for making this clear. Now I can incorporate the formulas into my programming code. However, I have one question - if the initial velocity is 10m/s, my own logic dictates that the sum of the velocities of both projectiles should add up to 10m/s. If I add the two velocities (5.18m/s + 7.32m/s), I get 12.5m/s, which is 2.5m/s over the initial velocity before the collision. Not sure if I'm thinking this right, I'm very new to this sort of thing

U r a hero💫❤

Great teaching! I have a question though: is there a way to determine θ1 (in this situation it's 30 degrees) if it wasn't given?

Why did you add the y components? Shouldn't you subtract v2fsin45 since it's acting in the negative direction?

you are my hero

In these types of problems, for kinetic energy conservation, elastic collisions, we do not separate x and y velocities to calculate kinetic energy of each object, before and after. It is simply the initial and final velocities of the balls, and then we plug those velocities in conservation of kinetic energy formula. And my question is why it happens this way? While we need to separate velocities in its components for conservation of momentum? pls answer

Please add these videos the mechanics' playlist doctor

I remember hearing that if 2 masses with the same mass collide, they bounce off at right angles to one another. I know that this example is just to get used to collisions in 2d, but would that collision be possible? I'm just wondering and not directly related to the question.

Collision problem 12 of 15 says elastic and has non 90° separation. Doesn't that imply 90° betwee two objects after collision. I tought other than 90° occurs if not perfectly elastic.

6:28 so we can take out the m' s because m1=m2? If so then what will happen if they were not to be equal?

Nice explanation sirr

Prof. I am getting a different answer. Can you tell me what I did wrong, please? I turned 10=v1fcos(30) + v2fcos(45) into [(10-v2fcos(45))/cos(30)]=v1f . Then I plugged it into 0= v1f sin(30) + v2f sin (45) and I got that V2f=-19.32m/s and V1f= 27.32m/s. I even did a system of equations on my calculator with v2f=y and v1f=x and I got the same results. I traced back everything and I cannot see where I went wrong. Even when I simplify the equations to decimals as you do in the video, so long as I substitute v1f into the 0=.... equation, I get the same answer, PLEASE HELP!!! Love your videos by the way.

How would you approach this problem if you wanted to find one angel and the velocity in that direction?

Although this problem seems correctly solved and the momentum values do check (sum of y components is zero, and sum of x components = 10), there is a traditional solution for off-center 2-D collisions which requires final velocities of the two balls to be separated by 90 degrees. Is this just an unrealistic theoretical problem, or is there an error somehow? (45 + 30 = 75, not 90)

Since you broke this up into the x and y components, how is it that you were still able to plug in the final velocity of mass 1 into the equation with the x components? I didn't know this was possible.

How would you do this if the bottom angle was not given?

An 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

You multiple v1f and v2f by 2 should you not balance it on the other side?

Lol im writing my physics exam in a few minutes. And this just helped me

Sir ,could you pls explain oblique ellastic collision in brief with numerical explanation

Love it sir

At 4:05, shouldn't it be MINUS m2V2f since the vector component is pointing down?

Sry to ask, but the kinetic energiy should be the same before and after, right? I tried but got: 1/2 * 10^2*m=1/2*7,32^2*m+1/2*5,18^2*m So about 50 = 26,... + 13,... But this doesn't make sense... Can someone tell the mistake?

Thanku sir .. really helpful 😊

excellent thank you! I can tell you actually care about teaching as a profession. Where in the world are you?

The question is, if initial momentum is not in the y-direction, what is compelling the balls to also move in y-directions?

Thanks

But Sir, what if the mass aren't equal? How about in 3D pleaaase help me.

the 45 degree is below x-axis, so it could have been specified that is negative.

thank_you.

Hi Michel... happy new year!!... I've seen a couple of Videos on Elastic Collisions using Billiard Balls. Both Balls have the Same mass... that is M1 = M2. The one thing these videos tended to point out is that when Two Balls of Equal Masses collide in an Elastic Collision.. the resulting ANGLES between the Two balls, After the Collision, always equals 90 Degrees... does that make sense?... I guess this assumes no Rotational Velocity was imparted to either of the balls during the Elastic Collision. I ask this because your video shows the angles AFTER the collision to be 30 degrees and 45 degrees... and the sum of those two angles = 75 degrees...... HELP!! lol... Thank you for another EXCELLENT presentation.... your clarity and "White Board Management" are superb...

why did u multiply 0.5 v1f by 2? i cant understand it :/. please answer asap

Sir this might seem a little awkward but gravity is an external force then how can momentum be conserved in the y-direction

RESPECTED SIR YOUR LECTURE ARE SO HELPFUL BUT SIR PLEASE MAKE ON ANGULAR MOMENTUM .

what will be direction after collision ?

What happens if I don`t have any angle?

thanks sir

Same question as jerry mike why did you multiply by 2 when doing y component?

How would you ever know the exit angles ahead of time?

Sir do you have any lectures on chemistry also ??

why u choose 30 and 45 degree is the collision not line of site

can the angles after collision be thesame?

so kinetic energy is gained after the collision?

the bowtie is a nice touch! :-)

if this is elastic, why isn't energy conserved? somehow energy is lost.

Nice vidios

Why did not you solve easier questions first, for example only v2f is unknown