00:01
Okay, so we are going to find the time, how long the airplane take to become airborne? we know it becomes airborne at 600 kilometers per hour.
00:10
So we're going to have to first find the derivative, and then we're going to set it equal to 600 and solve for the time variable, and that will give us what we want.
00:17
So the derivative of d is, in this case, 20 thirds t, and when you set that equal to 600, because that's the rate, 600 kilometers per hour.
00:27
So we're going to do 600 times 3 times each side by 3, and we get 20t equals 1 ,800, and then divide 1800 by 20, and we get 90.
00:40
So t equals 90 is the time, or how long it takes.
00:43
This would be 90 seconds is how long it takes...