Acceleration of aircraft carrier take-off | One-dimensional motion | Physics | Khan Academy

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Using what we know about take-off velocity and runway length to determine acceleration. Created by Sal Khan.
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[@Arunp47]

Couldn't you get the time taken by simply having displacement/average velocity?

[@akifukuzaki7457]

Why can't we use the equation for acceleration to reach this value instead? a=(delta)velocity/(delta)t We already converted the final velocity (Take off velocity) to 72.22, and so this would also be our (delta)velocity as we need to get from a velocity of 0m/s to 72.22m/s the (delta)t can be determined using the formula for displacement displacement is known because Sal gave us the runway length of 80m. 80m = Average Velocity ((72+0)/2) * (delta)t (delta)t = 80m/36m per second, or 2.22 seconds. and if we plug all of our variables now back into the formula for acceleration, a = (72.22 m/s) / 2.22 seconds a = 32.5 or 33 m/s^2 (there is a slight difference in the decimals which i don't entirely understand why, but would this be a viable solution as well?)

[@VishnuAi]

One of thee best physics video i have seen to Date! i really understood it! Thank you Sal Khan!

[@godandtechnodude]

THANK YOU SO MUCH DUDE I HAVE A PHYSICS TEST AND THIS HELPS A BUNCH YOU BROKE IT DOWN!!!

[@treeandplant]

I recommend to use this formula x-x0 = 1/2(v0+v)t and then substitute 80m for x-x0 and 72m/s for v to get t = 2.22 s.Substitute the value of 't' and 'v' in this formula which is v = v0 + at to get a approx = 33m/s^2.It's that simple.

[@slothfulsloth]

The best part is the pilot drawing!

[@eatcarpet]

I was like no way, so it takes off in about 1 second so I KZbind it and it did take off in about 1.5 seconds.

[@426F6F]

The last part, to figure out time he used the formula Δt= Velocity Average ÷ Acceleration, I was surprised that this gives the same answer as using Displacement ÷ Velocity Average to figure out the Δt. But when you think about it, it makes sense that they both equate to the same answer when using the decimal places for each variable. This is because the final velocity divided by the acceleration tells you how long it takes to get up to that speed with respect to acceleration, same as when you divide the distance (displacement) by the average velocity. Pretty basic when you break it down :D

[@ShreyaShukla-rn3bv]

the solution is big but if you use v^2=u^2+2as where v=final velocity, u=initial velocity, a=acceleration and s=here, runaway length, it would have been calculated in a minute btw the detailed solution is also nicely explained. good work

[@khanSanobar01]

I got 36ms^-2 as acceleration I did followed these steps 1. After getting initial and final velocity, i calculated delta t by displacement/avg velocity that is initial +final velocity by 2 2. Then i got 2 sec then i calculated acceleration upon its formula that is delta v by delta t and finally i got the above answer I used 72 as delta t Kindly suggest any correction that might be applied in my solution

[@sukhimoga]

Thanks Khan Academy.. ur videos help me alot .. :) !!

[@MyNamelsJohn]

Yay a new video!!

[@khmsalhuas1]

Khan, pls pls relativity theory i cannot wait to see u explain it! and if ur time permits, pls explain some of the quantum mechanics concepts. dude, I love ur soul ^^ Salam

[@jeenyus720]

thats a happy pilot

[@Aelfraed26]

Hal, an easier way to convert from km/h to m/s is to divide by 3.6, because 3600/1000 = 3.6.

[@hrn8935]

its sal and also thats right but i think he wanted to make it more intuitive

[@JimHoward]

m8tate is correct, the jet needs an >airspeed< of 260km, so you should have subtacted the wind speed and ship speed from 260. Sill, its a fun problem.

[@GenericCoder]

This makes me want to fly a hornet to know how it feel. Man you're awesome :).

[@JimHoward]

@DekraDaFurry - While the airspeed needed to fly is what it is, in order the takeoff roll is definitely influenced by the wind speed over the deck (V0 in Sal's equation). It's highly unlikely that the F-18 could make a successful takeoff if the ship was stationary with no wind. The cat probably couldn't accelerate the jet to takeoff speed and it would fall into the drink. Try this thought experiment. Could the F-18 make a successful takeoff if the ship was going 100 knots in reverse?

[@alexjohn9165]

best way to convert km/h to m/s is to multiply the magnitude with 5/18............ie....... given km/h= 36km/h. Covert to m/s. Therefore take 36* 5/18..... 36 and 18 gets cancelled.... we get 2*5..... Final answer will be 10m/s..... If its velocity metion its direction otherwise the magnitude is enough...... I hope this helps😄

[@freemanT0T]

We needed it bec-... Wait, 1 month old? What the heck. All we knew was how far the plane went, and how fast it needed to be going by the end of it. If the distance was 160 meters (twice as far) then the plane could accelerate at one half the speed (16.5 m/s^2).

[@DekraDaFurry]

@JimNtexas Actually, @m8tate is wrong, the ship speed won't influence the speed needed for takeoff. And about the wing resistance, we can't calculate that unless you got the aerodinamical characteristics of a F/A 18 Hornet.

[@piratemorocco]

@MK1999999 Spatium, it is the latin word for space (distance)

[@stoddcrew]

Don't you also have to consider the ships speed? It has an initial velocity of approx. 50kmh which is significant making the planes initial velocity of 50kmh if the ship is traveling forward in parallel with the runway.

[@Omnilegence]

I think the actual acceleration is a little higher by the end of the runway (which as mignik01 said is the ramp by the tower) due to the fact that I think the pilot often reaches take-off velocity before reaching the end of the ramp. I don't think the wind comment was very fair though (m8tate). Educational videos on KZbin can't be expected to successfully tutor people on mechanics whilst also involving friction, unless assumed to be constant.

[@vrdesk]

Khan uploads so fast

[@KeiferMac]

great job showing the concept instead of just telling the youngsters formula's! love the physics vids. please do computer science soon khan... i would love to see some oop languages!

[@rj23032]

Wow! 72 m per s is seriously fast, by the time my watch's second ticks once the flight wouldve travelled 72 m, hatsoff to the unit designed it to travel so fast. Now, why cant a small unit of it be made and then i could fly 72 m in a sec

[@andrenicholson6538]

if you want to calculate km/h to m/s just divide by 3.6 simple.

[@ur981]

Wait wait, I'm only 1:32 into the video, how are you able to use your mouse pointer like that in writing? You must have an amazing manual dexterity. ^5

[@danieldinh9911]

I think he might be using a graphics tablet.. Here's a link if you want to read more on it en.wikipedia.org/wiki/Graphics_tablet

[@jaytaffer9641]

1:15 If you want to be flying lmao

[@thonyea]

May I know where you got the specification of the F/A 18 Hornet?

[@jerfersonmatos28]

Maybe internet?

[@stoddcrew]

@JimNtexas Yes it could but only if there were a 200 knot wind traveling in the same direction as the ships travel(backward.).

[@martinojoker001]

I used this method : d=0,5*v*t 80=0,5*72*t --------> t=2,2222..... v=a*t -------> a=v/t a=72/2,2 a=32,4 Is it right?

[@abhimanyumimani6345]

makes more sense than what was done in the video.

[@Dexduzdiz]

this is soo sick!!

[@amimui1317]

so, what the result

[@Waranle]

260km/3.6s=72m/s :) Thnx Sal

[@epicman13ful]

I'm in grade 8 I can't remember things in classes ;p good videos thought I love math and science.

[@nauvalrifky3502]

So you're in college now?

[@EnvelopeCrease1]

The 80 meters is the displacement.

[@carolinischultz3730]

[@Waranle]

@Waranle 260km/h, even

[@dandandan3675]

6:56 Why isn't he using the FOIL method I'm confused.

[@dandandan3675]

Lol I just realized doing FOIL will just do the same thing

[@collinkenny3829]

Wouldn't the initial velocity be greater than zero due to the speed of the carrier?

[@jerfersonmatos28]

Assuming your statement then nothing stay at rest, sice the earth is aways moving

[@mintbrownieangelfish-6114]

it's all relative :) if the place you're comparing against is the earth, then yes, you're right. But he's comparing it to the boat surface, so the initial velocity is 0. I hope that made sense.

[@CrazyShooter199]

@TheNalu7 yeah sure

[@yakinthebox]

Why didnt you just use the formula Vf^2 = Vi^2 +2a times delta X

[@chanellbadri1598]

T=S/Va A=Vf/T Why go through all that

[@40404622]

I'm not sure if u know, but you can simply multiply km/h with 3,6 to get m/s an divide vise versa

[@eddie4071]

CrushDustHD Norsk Commentary what means 3,6

[@40404622]

Well, the people in the US might type . instead of , but it's simply an easy way of making m/s into km/h for example: if u have a car travelling at 40 km/h you can divide that by 3.6 and you will get (Answer m/s) and in this case the answer would be about 11m/s

[@weltirol3476]

oooh, like ... sure he knows, Sal Khan who made this video holds a MIT ( Massachusetts Institute of Technology ) Bachelor in mathematics and electrical engineering, a Master from the MIT in informatics / computer science and a MBA from Harvard Business School. But like already other people said: "He's showing you how you can deduct formulas and solve problems in many different ways using critical thinking, which is very important for advanced mathematics and especially in engineering." So he's not only teaching you Physics, but also the application of some of the most important techniques in science.

[@40404622]

Yes, I didn't know about his achievements when I wrote the comment. I just thought it would be smart to mention it :)

[@drgknght921]

when teaching something is always good to be as specific as possible, that's why if you notice, he never skips any details that might seem obvious to one, because you don't just assume the people learning knows

[@fredericozapponi9523]

Its not accurate as many already said, to takeoff and landing the carrier must be moving to reduce the airplane velocity... So, V0 is arround 50 km/h or 30 knots

[@youssefslm3542]

to change from km/h to m/s you can multiply 260(5/18)=72.2

[@youssefslm3542]

72x18/5 will go back to km/h

[@prav8141]

always dimentional analysis

[@eddie4071]

youssef slm what 18/5 means

[@calambuhayjr.josevirgiliog2094]

My accelaration is 32.4

[@m8tate]

This doesn't take into account the fact that jets on aircraft carriers take off into the wind, and the carriers themselves are also traveling forward with respect to the water.

[@mignik01]

and they take off and land on the same runway.

[@CDB1952]

v sub i should be at least 15 m/s - this is after all taking off from an aircraft carrier which would be moving at a good speed not to mention turned into the wind.

[@coltonwu1047]

Is is this physics 1 and 2

[@mignik01]

Thats not the runway. the runway is that slightly slanted one just to the right of that communications tower.

[@zgamer_5632]

Why don't we just do Time = Distance/Velocity, t=80/72 =1.1secs (and why was the Answer different)

[@callumcurtis15]

It is not always going 72 M/s it needs to accelerate to that peak speed .

[@zapxcero]

Did he just calculated the acceleration without time? WTF

[@calambuhayjr.josevirgiliog2094]

All i did is divide 72/2 =n then divide 80/n = 2.22 why yours is 2.18?

[@TheNalu7]

@CrazyShooter199 well this acount is my frineds that is legal age and they let me use it

[@cx1designs]

He lost me, on this one!

[@calambuhayjr.josevirgiliog2094]

Why my answer is 2.22sec

[@zwhitchcox]

Just want to point out none of these calculations account for drag, which is an extremely strong opposing force.

[@TheNalu7]

its also facts that matters

[@CrazyShooter199]

@TheNalu7 dude if you're in 7th grade you're not allowed to be on youtube.

[@karthikb4703]

I am mad what is this

[@Romis008]

I guess a pilot that is taking off of an aircraft carrier knows what it feels like to be REAAALLY fat

[@TheLittleMan123]

stop nagging about the aircraft and the way he put it. this video is about the math, not the aircraft carrier...

[@TheNalu7]

YOU SHOULD TALK YOU SICKEN ME

[@TheNalu7]

this video sickens me some thing called flight school they give you CORECT facts