Physics Lesson: Relative Velocity Part 1 Kinematics High School Tutorial

[hotpink8237]

OMGZ. you just taught me soooo much more than my own teacher.

[PhysicsEH]

@hotpink8237 Thanks for taking the time to let us know you liked our videos.

[KoolioJosh]

i had the most trouble with air plane problems, yet i found 2-d elastic collisions easy..

[sudoLinux666]

Thanks for these videos, and they surely help out.

Cheers!

[pinksugar1721]

amazing! you make physics make sense

[mcomeslast]

Yes thank you! This is quiet helpful.

[LILMattOwns]

thank you so much for the help!

[PhysicsEH]

@LILMattOwns Thanks for taking the time to let us know we helped. Best of luck with your course.

[Veerabit]

@PhysicsEH he got a 100 in the course.

[xxAlexLoves182xx]

werent you supposed to use 7.2 m/s instead of 6 m/s? because if you use 6 m/s you only count the time that would take the person to swim straight across excluding the waters affection on the swimmer

[PhysicsEH]

@xxAlexLoves182xx Surprisingly, the velocity of the water does not effect the time it takes to cross because the velocity of the river has no component or part in the direction across the river. If the river flows faster, you end up further down stream but you are still crossing at 6m/s toward the other side so it still takes the same time. If you consider the velocity triangle and the displacement triangle as a pair, it simplifies the solution (see 3:35) I hope this helps.

[trense13]

i wish you were my real physics teacher....mine is from north india....and its just like listening to popcorn pop.....thanks...this helped a lot..:)

[PhysicsEH]

@trense13 Glad we could help. Thanks for letting us know.

[RescuePits1]

Your explanation is well organized! Excellent video! Thanks for sharing! 

[PhysicsEH]

@RescuePits1 Thanks for the great comment. Glad we could help.

[PhysicsEH]

@BLeeMailMe Hi. The resultant velocity written at that point is a velocity but at the time I wrote it on the board I had just solved for the magnitude. The next step shown is solving for the direction. Once I have both the mag and direction I then write the final answer 7.2 m/s [E34S]. I hope this helps.

[Arijana2010]

Hey! Amazing videos, I just reccomend that you dont put the link in the corner of your videos as the time tab covers it when I go to click it. Maybe try somewhere in a corner? Great work!

[PhysicsEH]

@Arijana2010 Hi Thanks for letting us know. The time tab was not like that when we put the link up but now I will have to change it. We would not have known this without your comment, so thanks very much.

[toner4leeds]

im trying to study a second mechanical engineering applied dynamics module.. so.. no thanks

[pukawillive4ever]

WOWW this was really helpful..my life would never be the same

[PhysicsEH]

@pukawillive4ever Thanks for letting us know they helped. We love to hear that. Glad we could help.

[ReddAlertt]

I dont get the tip to tail thing. My teacher said I have to use that method for tests,

[PhysicsEH]

@ReddAlertt I know a lot of teachers use that method but I am not very familiar with it. If you have to use it, you should still be able to follow the logic in my example which will help you set up the equation. The tip to tail method I believe, is just how you draw the vectors when you add them and the diagram may even end up looking like mine. Both methods will result in the same answer. I hope the video still helps. Best of luck.

[rampriyadarshini]

thanks!

[aroy41]

I am not actually getting which vectors to add..and which 1 to subtract

[PhysicsEH]

@aroy41 Vr is what actually happens. The other velocities are what go into making Vr for instance in the case of a swimmer what happens Vr is a result of the swimmer swimming (Vs) and the water moving (Vw) So Vr = Vs + Vw.

For an airplane, what happens Vr is a result of the plane moving (Vp) and the wind moving (Vw) so Vr = Vp + Vw. The only time you get vector subtraction is when you are given Vr and need to solve for something else. When you rearrange the equation you might get Vp = Vr - Vw

[64647936]

Hi, sorry but i still dont understand y the adjacent velocity from theta is taken instead of the hypotenuse. I understand that although, as a column vector, the gain in horizontal displacement is the adjacent side, however why isnt the actual resultant velocity used instead? Or would they still sum up to the same thing?

[PhysicsEH]

@64647936 Sorry, your youtube question went in my spam box and I just found it.

You can use the resultant velocity and the actual displacement to get the time. But since the triangle made by the velocities is similar to the triangle made by the displacement, (video 4:33 s) you can also use the adjacent side velocity and the "adjacent" side displacement to find the time. It will work out to be the same.

[64647936]

@PhysicsEH Thanks!

[philylennon]

Nice vids but i'm after the vids on adding vectors in two reference frames??

[PhysicsEH]

@philylennon Hi. We hope to make more soon but I'm not sure if we will get to that topic. I hope the other videos are some help even if we don't have that one.

[SuCKeRPunCH187]

@PhysicsEH have you decided which topics your going to do yet?

[PhysicsEH]

@SuCKeRPunCH187 Not yet. It hink we may do some more on relative velocity and some more on graphing.

[PHDRelativePhysics]

May I ask your qualifications?

[PhysicsEH]

@PHDRelativePhysics Hi. We both teach at a school in Toronto, Canada. I have an engineering degree and the other teacher has a physics degree. We hope you enjoyed the videos.

[GhuneDhoraGuitar]

Sir, you are awesome.

[PhysicsEH]

@GhuneDhoraGuitar Hi. Thanks for the comment. Glad we could help.

[coronabob21]

I am currently a student at university in NC. I have a test tommorow and i honestly couldnt understand the book to save my life. After watching this video i feel amazingly more comfortable as i just had a problem like this i couldnt figure out. THANK YOU!

[PhysicsEH]

@coronabob21 Hi. Thanks for the compliment. We're glad the videos were some help. I hope your test went well.

[TheLightendarkness]

1st

Great video

now i don`t need to study this section. woohoo

[zixx0066]

@TheLightendarkness good for you, but dont say 1st, those people are always jackasses