
#1
Sep1304, 11:25 PM

P: 322

A light plane is headed due south with a speed relative to still air of 200 km/h. After 1 hour, the pilot notices that they have covered only 190 km and their direction is not south but southeast. What is the wind velocity in km/h and what angle it it north of east?




#2
Sep1304, 11:29 PM

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The velocity of the wind is the difference between the actual velocity of the plane and the "intended" velocity of the plane.




#3
Sep1304, 11:49 PM

P: 322

not really...in the book the intended is 240 km/h but the actual is 180 km and the answer they give is 170 k/h with an angle of 41.5 N of E.




#4
Sep1404, 12:02 AM

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help wanted 



#5
Sep1404, 12:26 AM

P: 322

but there's no angles given.




#6
Sep1404, 12:34 AM

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Due south and southeast sound like angles to me! :)




#7
Sep1404, 02:16 AM

P: 322

i still dont get it. angle is 45 degrees?




#8
Sep1404, 02:31 AM

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LaTex doesn't seem to be working so I'll try this:
The actual speed of the plane is 190/sqrt(2) km/h so it's actual velocity is (1, 1)*190/sqrt(2). The "intended velocity of the plane is (0, 1)*200 km/h. The difference between them is the wind velocity: (190/sqrt(2), 200  190/sqrt(2)) Now just divide the y component by the x component to find the tangent of the angle you're looking for. A drawing might help you see it better. 



#9
Sep1404, 08:17 AM

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Thanks
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#10
Sep1404, 12:17 PM

P: 322

Tide, Does Latex work now? I still don't get the answers that the book got using what you did...



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