## Babynini one year ago Airplanes and vertex

1. Babynini

2. Babynini

@perl

3. Babynini

@freckles

4. Babynini

@gaos :)

5. ganeshie8

velocity of jet is 775 mi/h in NE direction : |dw:1433303568557:dw|

6. ganeshie8

can you split it as horizontal and vertical components ?

7. Babynini

em nah i'm not sure.

8. Babynini

you mean like make it into triangles?

9. ganeshie8

Yes solve these two sides in the right triangle |dw:1433304188744:dw|

10. Babynini

the side along j is 548.007 ...right?

11. Babynini

no, sorry. the side from the j line to the plane

12. ganeshie8

548 is right

13. Babynini

oh haha good!

14. ganeshie8

|dw:1433304779704:dw|

15. ganeshie8

so for part $$b$$, the velocity of jet in component form is $\large 548i + 548j$

16. Babynini

ok!

17. Babynini

can we do the same for the wind and get 27.5? or does that not work?

18. ganeshie8

you need to work horizontal and vertical components in this triangle |dw:1433306300948:dw|

19. ganeshie8

horozontal = 55*sin(30) = ? vertical = 55*cos(30) = ?

20. Babynini

27.5 47.63

21. Babynini

(horizontal first, vertical second)

22. Babynini

is the direction of the jet (the last box) = 58.64?

23. Babynini

(sorry, tht's a completely different part. we can come back to that.)

24. ganeshie8

good so for part $$a$$ do we have $\large 27.5i + 47.63j$ ?

25. Babynini

Yup

26. ganeshie8

For part $$c$$, simply add the answers from part $$a$$ and $$b$$

27. ganeshie8

hey may be use 548.0077i + 548.0077j for part a because they are asking to round to two decimal places

28. ganeshie8

part $$c$$ : true velocity of plane = velocity of plane + velocity of wind = $$\large (548.007i+548.007j) + (27.5i+47.63j)$$ = ?

29. Babynini

575.51i +595.62j

30. ganeshie8

you should be getting 575.51i +595.6$$\color{red}{4}$$j check once

31. Babynini

hm ok. Maybe i rounded the numbers wrong. I tried to use the original numbers.

32. ganeshie8

ok part $$d$$ should be simple take the magnitude of true velocity vector from part $$c$$

33. ganeshie8

speed = $$\|575.51i+595.64j\| = \sqrt{575.51^2+595.64^2}=?$$

34. Babynini

828.25

35. ganeshie8

knw how to work last part ?

36. Babynini

uh well I think so but i've been getting lots wrong lately lol

37. ganeshie8

for last part, just need to find the angle of true velocity vector from part $$c$$

38. Babynini

equation for that would be?

39. ganeshie8

For any vector $$x+iy$$, angle with positive x axis is given by $$\tan^{-1}(y/x)$$

40. Babynini

so we'd do tan^(-1) 595.64/575.51

41. ganeshie8

yes use ur calculator

42. Babynini

45.98

43. Babynini

oh but rounded to nearest interger so 46?

44. ganeshie8

yes but thats the angle from positive x axis : |dw:1433308877835:dw|

45. ganeshie8

the question is asking you for the angle from positive "y" axis

46. ganeshie8

|dw:1433308980730:dw|

47. Babynini

44

48. ganeshie8

Perfect!

49. Babynini

haha yay! :)

50. Babynini

51. Babynini

Did i put them in wrong? o.o because the answers based off of those are correct.

52. ganeshie8

how many chances do u have ?

53. Babynini

5!

54. ganeshie8

5 or 5!=120

55. ganeshie8

try putting exact form

56. Babynini

oh gosh no lol just 5.

57. ganeshie8

part $$a$$ : $\large 27.5i+27.5\sqrt{~3~} j$

58. ganeshie8

part $$b$$ : $\large 387.5\sqrt{2}i+387.5\sqrt{2}j$

59. Babynini

Yeah the example one they did looks sort of like that. just divided b by the sq2

60. ganeshie8

good, give it a try you have 3 more chances right

61. Babynini

so should I do it exactly like them and try to put little arrows over stuff?

62. ganeshie8

do u knw how to put arrows ?

63. ganeshie8

maybe forget about arrows for now and try entering the exact values wid radicals if it doesn't work, then you may try with arrows

64. ganeshie8

because part c worked even when you didn't put arrows

65. Babynini

not dividing it by sq2 either?

66. ganeshie8

enter these and let me know if they work http://gyazo.com/81f10a84809d5f9dc852b18b923080a3

67. Babynini

Yep that did it :)

68. ganeshie8

Awesome!

69. Babynini

Many thanks ^-^

70. ganeshie8

np