Race cars with constant speed around curve | Physics | Khan Academy
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- Опубликовано: 15 сен 2024
- When acceleration could involve a change in direction and not speed. Created by Sal Khan.
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conclusion: acceleration is produced by changing in velocity's magnitude or its direction or both at the same time
THANKS FOR THE TIME AND EFFORT FOR US ALL. my kids and i benefit!
Khanacademy saves my life again.
@engmustafa83 Good point but that would relate to angular velocity. "The rate of change of angle with respect to time" Acceleration refers to the rate of change of linear velocity. The car is moving along a tangent to the curve at any point during the turn. Therefore the direction(tangential velocity) is changing and so is it's acceleration.
Hope I helped.
@khanacademy
Wasn't trying to make any point, I was just trying to make fun of hypothetical physics. Most of the scenarios are so absurd. I remember in High School calculating the thermal expansion of a continuous ring of steel that was around the earth's equator, to establish how high above the surface it would be if it raised the tempreature of the steel raised by 1C.
Do you have a lecture on banked curves? Your videos are extremely helpful especially when reviewing before tests, but this is one thing that I'm not great at and I couldn't find a video on it.
@mohalfur as a driver, I do autocross, there are three stages to a turn, turn in, mid-turn and exit, and you are not doing the same thing with the car at anyone point. Just before turn in you will have slowed to the speed necessary to make the turn, at turn in you are coasting, as you get to mid turn you are accelerating to keep a constant velocity and the tires just inside the edge of adhesion, and at turn exit you are accelerating as hard as possible. Hope that helps.
@qbrt Thnx a lot! Great that its coming from a driver.
tyvm :)
@b0b0maj0 He's not increasing his speed. He could have already slowed down to 100 km/h for the turn and held it there for the turn.
Sal, please make more hedge fund videos, especially focusing on the startup and mangerial jobs.
Very intersting
Please tell me about the Laws of Physics applies When Doing Bike wheelie.
So this is about the different between speed and velocity.
I first thought they weren't accelerating but then I thought about how when you go around a curve your body gets jerked around. If acceleration wasn't occurring, you wouldn't get jerked around. Is that a useful insight?
Thanks for making learning physics fun once again!
@engmustafa83 Lets say It turns on a fixed diameter. The car is turning, but at each point during the turn he is heading in a straight line. The car's turn is made up of thousands of dif directions of where it faces at each second during the turn. Therefore if its direction is changing so is its velocity and its acceleration.
The problem you describe is a lot more complicated than that. And you don't reduce acceleration by slowing down, you reduce velocity. But the scenario of a car going around a sharp turn involves torques twisting the body(literally trying to flip the moving body over) in addition to centripetal acceleration. There's a large collection of partial differential equations which give you the total solution, but understanding all of it at once is even beyond me and probably Sal currently.
Icyveins906 Actually, he just showed these cars for and example. For a better understanding he removed all other variables. Like the mass of the car for example. Or gravity or Friction from the ground. We just assume that an object with a definite velocity is in motion around a circular path. The only variables to take in account are the objects velocity and acceleration.
@b0b0maj0 it's tricky because we non-physicists use acceleration to mean "speed up" but physicists use it to mean "change speed and/or direction" which I guess is what the video is getting at. So they aren't pressing down on the accelerator (I hope!) but they are experiencing the physical force of acceleration, which is what makes your body lean outward as you go around a curve (I think)
Could you show it mathematically too
@khanacademy
If you want the car to have the best possible traction around a curve, should you:
1. accelerate, 2.deaccelerate or 3. keep a constant speed through the turn?
Please Sal answer (Me and my friend are having a big discussion)
Acceleration must be happening because the velocity in the direction of the turn was 0 and became 100
awesome example! thank you!
classical dynamics is good for the soul
A way of explaining it, would be to decompose the velocity and acceleration vectors in their axis components and make some graphs about it :P
It funny how speed and velocity often mean the same thing when used in other contexts.
@b0b0maj0 vector acceleration does not change the speed if it is perpendicular to the movement, simply changes the direction of the vector velocity. Sal will probably explain this using the Work equation. Wait for it, you will understand it quite easily.
im in science class right now
@b0b0maj0
You missed the point of this and the previous videos! This is not driving school, it's physics ;)
DNA zincirindeki sarmal gibi,virajın olduğu çizgileri hidrojen bağları olarak düşünürsek,bu viraj tam yuvarlak ve içi kırmızı, beyaz çizgiler olabilir.Yan kesit olarak arabanın tekerleğini fosfat grubu diyebiliriz ,arabanın şeklinide ,organik baz diyebiliriz.
Oooh, tangents.
Just an observation, hot pockets make khanacademy sooo much better.... actually forget that, they make everything better. what does this have to do with physics? NOTHING!!!!!!
IIIMMM DON'T KNOW WHAT I'M SAYING
Pi eventually does end. :D
WHAT
@NewgroundsOwnSBB exactly.
I paused at 1:19 around 20 minutes ago...
Still haven't pressed play yet...
I'm no expert and this very well may be wrong, but when u accelerate it takes energy to speed up and if you turn you lose energy so if you want to maintain that speed you need to add energy or you slow down
you sound more excited in this one
So how fast would the earth have to spin before we felt it?
You are how I passed Calc I...I hope you can help me pass physics (:
+#feelthebern 2016 we wanna know now!
Hey, Sal, you should fix the spelling from "constand" to "constant."
I keep thinking the slingshot effect.
I only ask Nature of acceleration
Speed isn't acceleration. Acceleration is the increase of speed
If a car is moving with constant speed what is nature of it acceleration. Please give me answer
The car is accelerating because the direction is changing. Velocity is a vector quantity meaning it has a direction. As it goes around a curve, the car changes its direction which changes it's velocity. Acceleration in the change in velocity over time. Because the car changed direction, it changed velocity, and therefore, the car changes it's acceleration.
but they increase their speed after they have passed through the vertex of the curve
Albert Dwinov Levanka / 01 / XTPGM /
Centripetal acceleration= V^2/R.😁😁
You're assuming that there's friction.
i understand this is to explain physics, but it seems questionable that a racing driver would accelerate turning into a corner
When you use cruise control instead of trail braking FeelsBadMan
Patrick Bateman
Was the math ever done for this??
In a circular motion, I don't think speed and magnitude of velocity is the same. For example when a covers half a circle, speed = πR/t and magnitude of velocity = 2R/t
imo, the driver slows down a car simply because otherwise his tires could not provide enough static friction (or grip) and therefore, a car could not accelerate enough (by changing direction) to go through a corner. So the driver simply reduces the amount of acceleration needed to go through a corner by slowing down.
Hey, sal do face reveal
I don't this topic is that easy to explain. I didn't understand his explanation.