Name: 空中客車A380起飛時間｜一維運動｜物理學｜可汗學院。 (Airbus A380 take-off time | One-dimensional motion | Physics | Khan Academy)
Uploaded: 2021-01-14T06:34:30.000Z
Duration: 8 min 8 s
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This right here is a picture of an Airbus A380 aircraft.

And the specs I got were 280 kilometers per hour.

And to make this a velocity we have to specify a direction as

So the direction is in the direction of the runway.

So that would be the positive direction right over there.

So when we're talking about acceleration or velocity

in this direction, the direction of going down the runway.

And I also looked up its specs, and this,

I'm simplifying a little bit, because it's not

going to have a purely constant acceleration.

that the pilot says we're taking off to when it actually

takes off it has a constant acceleration.

Its engines are able to provide a constant acceleration

So after every second it can go one meter per second

faster than it was going at the beginning of that second.

Or another way to write this is 1.0-- let me write it

can also be written as meters per second squared.

So the first thing we're trying to answer

That is the question we will try to answer.

in terms of meters and seconds, or seconds squared.

And over here we have our takeoff velocity

So let's just convert this takeoff velocity

And then it might simplify answering this question.

how do we convert that to meters per second?

So let's convert it to kilometers per second first.

Or what do we put in front of the hours and seconds?

So one hour, in one hour there are 3,600 seconds,

60 seconds in a minute, 60 minutes in an hour.

And if we do that, the hours will cancel out.

And we'll get 280 divided by 3,600 kilometers per second.

So let's also do the conversion from kilometers to meters.

So once again, we have kilometers in the numerator.

So we want the kilometers in the denominator now.

And we have 1,000 meters for every 1 kilometer.

And so when you multiply this out the kilometers

And you are going to be left with 280 times 1,

so we don't have to write it down, times 1,000,

all of that over 3,600, and the units we have left

are meters per-- and the only unit we have left here

So let's get my trusty TI-85 out and actually calculate this.

So we have 280 times 1000, which is obviously 280,000, but let

And it gives me 77.7 repeating indefinitely.

And it looks like I had two significant digits

Was the spec rounded to the nearest 10 kilometers?

Or is it exactly 280 kilometers per hour?

So we only have two significant digits here.

So we should only have two significant digits

So we're going to round this to 78 meters per second.

So this is going to be 78 meters per second,

For this thing to take off every second that goes by it

of the length of a football field in every second.

But that's not what we're trying to answer.

We're trying to say how long will take off last?

Well we could just do this in our head if you think about it.

The acceleration is 1 meter per second, per second.

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空中客車A380起飛時間｜一維運動｜物理學｜可汗學院。 (Airbus A380 take-off time | One-dimensional motion | Physics | Khan Academy)

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