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Mathematics 7 Online
OpenStudy (anonymous):

A small airplane takes of at an airspeed of 180km/h, at an angle of inclination of 14 degrees toward the east. A 15 km/h wind is blowing from the southwest. Determine the resultant ground velocity.

OpenStudy (shamim):

i think i will b able to solve it

OpenStudy (anonymous):

It's something to do with the unit vectors, but after I get them, I'm at a loss because I don't know what's next to do with them. The one with the initial air speed's unit vectors are: x=180scos14, and y=180sin14

OpenStudy (anonymous):

But after that, I'm lost

OpenStudy (shamim):

so u wanna know the resultant ground velocity

OpenStudy (shamim):

i think wind velocity will b \[15i-15j\]

OpenStudy (shamim):

and the result of ur question will b \[180 \cos 14+15 \cos 45\]

OpenStudy (shamim):

m i right

OpenStudy (shamim):

do u wanna c details

OpenStudy (anonymous):

Details please. Sorry for the late reply

OpenStudy (shamim):

ok

OpenStudy (shamim):

the ground component of the plane speed of 180 km/h is 180cos14

OpenStudy (shamim):

and this ground component is along east

OpenStudy (shamim):

next the component along east of wind speed (15) is 15 cos 45

OpenStudy (shamim):

then i just add those

OpenStudy (anonymous):

And it's 45 degrees because of the fact that it's coming STRAIGHT from the SW right?

OpenStudy (shamim):

ya i think so

OpenStudy (anonymous):

how would you get the angle?

OpenStudy (shamim):

i guessed

OpenStudy (anonymous):

Alright. I'll try to get it in some way :P. Thanks for the help

OpenStudy (shamim):

thanks for medal

OpenStudy (shamim):

anyway if u wanna know just the resultant velocity of ur plane then the result will b different

OpenStudy (anonymous):

How would you get the resultant plane velocity?

OpenStudy (shamim):

i wanna introduce unit vector here

OpenStudy (anonymous):

i and j being x and y respectively

OpenStudy (shamim):

ya i,j,k will b along X,Y and Z axis

OpenStudy (shamim):

unit vector

OpenStudy (anonymous):

And then, how do you get an absolute answer from those?

OpenStudy (shamim):

ok

OpenStudy (shamim):

i was wrong

OpenStudy (shamim):

actually the plane velocity will b 180 cos 14 i+180 sin 14 k

OpenStudy (anonymous):

Alright, then you just add those and get the answer?

OpenStudy (shamim):

ya

OpenStudy (shamim):

n we can get absolute number too

OpenStudy (shamim):

now wind velocity will b 15 cos 45 i+15 sin 45j

OpenStudy (shamim):

so the resultant velocity of ur plane will b 180 cos14i+15cos45i+15sin45j+180sin14k

OpenStudy (shamim):

absolute is \[r=\sqrt{x ^{2}+y ^{2}+z ^{2}}\]

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