Centripetal Acceleration (part 3)

[schmiigle]

*it was useful



[schmiigle]

'i don't know is that was disturbing or useful or confusing' heehee

[Kricardose]

I am very happy to see the vidoe How fast does a car need to go to complete a loop-d-loop after you give this

[bebeheuy]

I Love The Video It Can Increase My Knowledge How fast does a car need to go to complete a loop-d-loop.

[Mjhond]

Steady I Really Like This Video How fast does a car need to go to complete a loop-d-loop

[gigaguy101]

Watching your videos makes me want to be home-schooled.

[DoctorBlissful]

Sal, your videos are comforting.

[FlagsSC]

@bubbleteddies Because Fn and Fg act as Fc (the force towards the center) so I considered both of them when doing the formula Fnet=mac

[FlagsSC]

7.71m/s (for the answer below)

[FlagsSC]

Please correct me if I'm wrong but I dont think this is correct. Since you're trying to find the minimum speed it must go to offset the loop, shouldn't you consider Fn as a force as well. Fg and Fn are both going downwards so according to newtons second law the equation would be Fg+Fn=ma. Fn must be 0 as that is the minimum to complete the loop, making the equation Fg=ma. Fg=mg and a=v^2/r so the new equation would be mg=m(v^2/r). Masses cancel out so the new equation is g=(v^2/r) making v=7.71

[EV5852]

It's weird he talks like any other teacher but his voice keeps me interested, that and the fact that I need to pass physics

[vladaman1]

can you make a video where speed is not constant (like the car has some kind of force on it) because i get all messed up when the it's changing and i really don't know what to do

[grybok1ng]

Sal; is there any way you could make a video about liquid-liquid centrifugal decanters and how we determine various radial distances from the axis of rotation? Im stuck on these problems and I never get stuck... =o

[greent26tube]

What about mass? Why wouldn't the force be gravity times the mass of the car?

[LuminaFlux]

How can gravity be considered a centripetal force? Provided that a centripetal force is a force that projects inward to the center of the circle, gravity does not behave this way, right?

[zeronebula100]

Take the moons revolution around the earth for an example. The earth provides a good inward force for the moon to stay in that path without shifting off the elliptical path its preforming. Its more basic than you think. As for black holes this object will spiral into the black hole

I get what you are asking that gravity doesn't make it to be a centripetal force because it doesn't make an object go to the center of the loop, but in this example he used the loop as the circle and gravity as force

[lolololort]

@LuminaFlux

Ofcourse it does. Earth is a sphere and gravity pulls you to its centre..

[LuminaFlux]

@lolololort To the center of the earth, but not the center of the pertinent loop! Right? Or is this intuition flawed?

[lolololort]

@LuminaFlux

the centre of earth is the centre of the circular path around earth. Just draw it out and you'll see. You'll probably have on of those 'Ooooh, how could I be so stupid'-moment :p

[cooldudetanmaya]

where did u get 32 ft/s from ? -.-

[Malookii96]

Thank youu!!! :D

[beboboy67x]

20feet you trying to get a real car to round that

[demonangels67]

Your example is quite disturbing xD

[SimoneETC]

where did you 32ft/s^2 from??? random? cuz thats what i wanna know how to find!

[534coolio]

@SimoneETC

That is just the acceleration of gravity (which is about 10m/s^2 converted to feet. He probably did this because the radius was given in terms of feet.

[mrmasta50]

@SimoneETC its gravity in ft instead of m

[Goodfellow7]

Going off the diagrams I would of hated to see the mess your room would of been in when you was in college!

[MusiQKisLiPHe]

this makes me wanna play sonic the hedgehog

[floweriess]

I had previously lost my faith in ability to do well in physics, but these videos have helped me more than you can imagine. Thank you so much!

[beshika]

U deserve an award for doin this! Thank u Sal!!!!! =D

[beshika]

U deserve an award for doin this! Thank u Sal!!!!! =D

[alinor2]

I like the heroine example :)

[edmundstoiberderdepp]

feet? arbitrary rollercoaster, but good movie nonetheless :D

[shinobimanexe]

hey i like it all the way through! this simplifies alot but i have a question for you, i am a game developing stundent and vectors are my buisness unfortunately im no good with them ha ha that being aside, say there was a driver in the car, when the driver pushes down on the petal at the enitial starting point, what would the movement equation be assumeing the equation will accept the pressence of an upward curve and or loop as seen here, please explain your variables thank you ^_^

[MarvelsofaLifetime]

Lol I loved how Sal digressed on that tangent at the end.

[redmickeys]

ahh! I love you! Thanks SAL!:)

[light2pink]

What do you mean when you say "the velocity is always tangent..." I've heard that a couple times, and I don't know what that means. 1:50. It was in your past video, too

[Chiborino]

@light2pink

It means that if you pick a point in a circular path, the velocity will make a right angle to the radius.

[MilitantBlackGuy1]

I don't like how he implies that the effect of gravity starts at a certain point :P I think you'll find the car would do a loop-d-loop without any help if the effect of gravity suddenly 'started 'pulling' down'. I hate that phrase anyway though gravity isn't a force read up on general relativity 8)

[Chiborino]

@MilitantBlackGuy1 You leave relativity out of this D:<

Seriously, though, no need to bring Einstein into calculations on amusement park rides.

[MilitantBlackGuy1]

@Chiborino There might be no need but teaching Newton's laws as if they're a fact is bullshit. He was wrong. I don't care if his calculations were much more simple and accurate enough to provide good answers for most things, schools still should not teach them like they're a fact

[Chiborino]

@MilitantBlackGuy1

I see them more as a foundation for later stuff. As wrong as Newton may have been, if you throw Relativistic motion at a High School physics student, they probably won't know what you're talking about.

Now, if you introduce Newton's Laws prior to that, and build from there, I think it's a much better way to get someone to understand it. Start small, build from there.

[yo3443]

@MilitantBlackGuy1 wtf are you talking about?

[MilitantBlackGuy1]

@yo3443 Einstein's theory of general relativity. The modern day accepted theory of gravity. Which states that gravity is not a force.

[akbankush]

I would also like to know what is the force called which acts at the outward direction of the circular motion

[noblessus]

@akbankush: I think you are referring to Newton's first law: which Galileo called "inertia", and which some mistakenly call "centrifugal force".

[akbankush]

@noblessus but friend i was actually talking about the force that acts on us when we are on a circular motion like on a fast merry-go-round we tend to feel an outward force which takes us away from the center of the merry-go-round and tends to throw us out.(i know about centrifugal and centripetal force but this term i am not able to remember)

[akbankush]

@noblessus but friend i was actually talking about the force that acts on us when we are on a circular motion like on a fast merry-go-round we tend to feel an outward force which takes us away from the center of the merry-go-round and tends to throw us out.(i know about centrifugal and centripetal force but this term i am not able to remember) i even know about newtons three laws.

[akbankush]

@noblessus but friend i was actually talking about the force that acts on us when we are on a circular motion like on a fast merry-go-round we tend to feel an outward force which takes us away from the center of the merry-go-round and tends to throw us out.(i know about centrifugal and centripetal force but this term i am not able to remember) i even know about newtons three laws. you can even try the experiment on a merry-go-round.

[noblessus]

@akbankush Yes! that force which pulls us outward is nothing else than Newton's first law: Inertia. Our natural tendency when given velocity would be to travel in a straight path, but the merry-go-round not only keeps giving us velocity, but also keeps counteracting Inertia by changing our direction as we move (with friction and normal forces). And as long as we have this velocity we will feel the effects of inertia which want to take us along a straight line tangent to the circle.HopeThatHelps.

[tadm123]

@akbankush the velocity of the car?

[akbankush]

you could use metric system which would be handy .I would also like to know more about circular motion.

[Minandreas213]

I like an unhappy ending on occasion. It makes things interesting.  SQUISH HER!

[ahomnky]

why can't you use metric units like m/s?

[toob94]

For a second I did not notice the acceleration of gravity is in ft/s^2 any one else who panicked gravity is still 9.8 meterss/second^2

[UberCuba]

Wouldn't you say the velocity would be coming from the cars centre of mass instead of the bottom, and wouldn't that change the "radius" of the center to the car.

[izi2bhappy]

i never get tired listening to you

thank you

[DonRoddelito]

@izi2bhappy But there is one thing that is wrong about the video, when the car is at the top position, the car doesn't push the ''floor'' upwards. It doesn't because the whole point of a_c is the inner force

[almanulinux]

Hi. Since it seems you say the "centripetal" acceleration always points to the centre, at the upper point the centripetal acceleration points down and adds to "g", isn't it? So, the car would always fall down, no? Because there is no acceleration able of opposing its weight... or am I loosing something? Thanks.

[mygremg]

if you are to apply gravitational acceleration, the radius should be the distance from the center of earth to the point where car stands in the loop. anyone can tell me why the radius of loop was used here?

[xxxmidgetmanxxx]

You would use that if your trying to figure out how much gravity the earth is exerting on the car, not how fast the car needs to be going to escape the downward pull of gravity...if that makes sense.

[Rawr454]

You want to keep the car where it stands, not on the earths surface, so ignore it's radius , or just add it to the cars distance from earths surface if a question asks.

[Rawr454]

For another example, The track acted as the point where the radius ends, for obvious reasons. With the earth, we were discussing it's force, so we took the radius of it's force circle, not the planet itself.

[abualiisthebest]

y are u doing it ft/ sec most people in the world use meters but thanks good video

[skyfaze]

cuase hes from america!!

[degoi]

great videos! Sure, but why from one moment to another he start using feet's as the magnitude ? in my country we use meters and I am not costume to feet's. Even do, that's not a big deal.

[novatodeguitarra]

actually the velocity you get has to be the one at the upper point of the loop I mean if is starts at some velocity when it starts "climbing" it's cinetic energy will turn into potential energy assuming there in no how do you say "rozamiento" between the floor and the car at the beginning you'll have some cinetic energy (m.v(i)^2)/2 and in the upper point you'll have cinetic plus potential m.v(f)^2+m.g.2r it's good as an example for centripetal acceleration but if you have that problem at a test

[amankus11]

Haha I love the example with the heroine! Hilarious!

[daltonistaako]

where did you get the 640?

[megaelliott]

32ft/s *20=vi^2

a=(v^2)/r

[megaelliott]

sorry didn't mean to put i

[tnagan]

I loved this video, especially the disturbing part. Thank you Sal, from Seattle, WA! This concept makes more sense to me now.

[brentwoodbc]

Just use metres though....

[Duckalore]

How much is one feet in meters. Never used feet before.

[brentwoodbc]

3.2808 feet in 1 metre

[duckj7]

what about if the track has a coefficient of 0.2 or something like at

[airlinecaptain]

It wont matter.

There is no frisction variable in the equation, thats maybe involved in centripetal force, where you use mass aswell.

[arkaridge]

Thanks. for this. I found it useful. =]

Although I do prefer metric units.

good job

[sokkakings]

Nice, thanks again, "I dont know if that was useful or disturbing..." hahaha

[bloodjunkiepr18]

You're a terrific instructor and thanks to you I finally understand what they teach me at school. but I'm dead serious, you MUST make a vid of you explaining something scientific, while drunk. That'll be my fav. vid of all time.

[psychologicalshock]

Thanks a lot for these videos.

[RomanticDaydreamer]

I was a bit confused at the end, but very good video. Thanks so much for making these, they're really helpful. Keep up the good work! :)

[maxhawkins]

Your lack of metric units is disturbing. Good video, though.

[Justen1980]

@maxhawkins whatchu need metric fo cept when you buyin cocaine it come in grams

[robit99]

your lack of SI is just as disturbing

[chopperhead2011]

I think I get it

[darkwspyder]

LOL I like that heroine story!