00:01
You have a plane flying with a velocity relative to the air of 800 kilometers per hour west.
00:08
So i made that negative.
00:10
P representing plane, a, representing air in my subscripts.
00:15
You have the velocity of the air with respect to the ground of 90 kilometers per east.
00:19
I made that positive to reflect the easterly direction.
00:22
You're told that the distance the plane is going to travel is 1 ,200 kilometers.
00:27
Initially, the plane is flying against the wind.
00:30
So you need to find the velocity of the plane with respect to the ground.
00:35
So since my subscript is in correct position, p -a -a -g, if i combine those together by addition, you get negative 800 kilometers per hour plus 90 kilometers per hour.
00:52
You get an answer of 710 kilometers per hour, and it's negative because it's going to be west.
01:01
The problem is asking about flight time.
01:07
So given i know d and v, i can say that t equals d over v or 1 ,200 kilometers divided by 710 kilometers per hour...