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# M1 Help! Urgent!!! watch

1. I am absolutely terrible at M1... Please explain this as well as you can.

Question: A plane flies due north at 300kmh^-1 but a crosswind blows north-east at 40kmh^-1. Find the resultant velocity of the plane and its bearing (to the nearest degree).

HEEEELP!
2. draw a picture... first line going north length 300,

second line going northeast starting at the top of the other line length 40. the third side of the triangle gives you the answer.
3. (Original post by the bear)
draw a picture... first line going north length 300,

second line going northeast starting at the top of the other line length 40. the third side of the triangle gives you the answer.
That seemed to be the logical approach from my point of view (assuming that you are basically talking about pythogoras, right?)
So I did it and I got 302.65 (2dp) answer, but my teacher's answer states that it should be 329.5... Am I missing something or is his answers wrong?
4. (Original post by saule1116)
That seemed to be the logical approach from my point of view (assuming that you are basically talking about pythogoras, right?)
So I did it and I got 302.65 (2dp) answer, but my teacher's answer states that it should be 329.5... Am I missing something or is his answers wrong?
it won't be a 90° triangle so Pythagoras won't be much use.
5. (Original post by the bear)
it won't be a 90° triangle so Pythagoras won't be much use.
Oooohhhhhh.....

So... That's because the crosswind is north-east, right?
So do I use Sine rule/Cosine rule to solve this? I don't know any angles.. :/
6. (Original post by saule1116)
Oooohhhhhh.....

So... That's because the crosswind is north-east, right?
So do I use Sine rule/Cosine rule to solve this? I don't know any angles.. :/
mwhahaha but you do know an angle... north-east is a particular angle direction ?
7. (Original post by the bear)
mwhahaha but you do know an angle... north-east is a particular angle direction ?
..is that 45 degrees? (I don't know what I was thinking when I picked maths. xD All I can do is algebra. )
8. (Original post by saule1116)
..is that 45 degrees? (I don't know what I was thinking when I picked maths. xD All I can do is algebra. )
Yeah 45 degrees
9. (Original post by iscribbletoomuch)
Yeah 45 degrees
Woop woop! I'll give that part another shot
10. (Original post by iscribbletoomuch)
Yeah 45 degrees
I got 273.18 (2dp), this still doesn't match my teacher's answer! I used the Cosine rule.
11. Oh you are using 45 degrees as your angle, you should use 135 degrees!
12. (Original post by iscribbletoomuch)
R^2=300^2+40^2-2x300x40xcos45(degrees)
13. (Original post by saule1116)
R^2=300^2+40^2-2x300x40xcos45(degrees)
Basically, 45 degrees isn't the angle to use, you should use 180-45 since the vectors effectively stack up
14. (Original post by iscribbletoomuch)
Basically, 45 degrees isn't the angle to use, you should use 180-45 since the vectors effectively stack up
THANK YOU SO MUCH!!!!! (I would share my cookies with you!)
It works! That's almost like magic! Yay!
Thank you! ^^
15. (Original post by saule1116)
THANK YOU SO MUCH!!!!! (I would share my cookies with you!)
It works! That's almost like magic! Yay!
Thank you! ^^
Maybe it is magic

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Updated: November 8, 2015
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