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19. An aircraft maintaining a constant airspeed of 525 MPH is headed due south. The jet stream is

120 MPH in the northeasterly direction.

a. Sketch the scenario on the x-y axis.

b. Express the velocity of the plane relative to the air as a vector.

c. Express the velocity of the jet stream as a vector.

d. Find the velocity of the plane relative to the ground.

Find the actual speed and direction of the plane relative to the ground. Round to the

tenths.

e.


Sagot :

Answer:

a. Sketch is given in the attachment

b. [tex]V_{p}[/tex] = (0,-525)

c. [tex]V_{w}[/tex] = ([tex]\sqrt{2}[/tex],[tex]\sqrt{2}[/tex])  

d. [tex]V_{g}[/tex] = (60[tex]\sqrt{2}[/tex], 60[tex]\sqrt{2}[/tex]  - 525)

e. Actual Speed = |[tex]V_{g}[/tex]| = 448.3 MPH

Direction = Ф = - 79.1°

Direction = Ф = 280.9° with respect to x - axis.

Step-by-step explanation:

a. Sketch the scenario on the x-y axis.

Where,

Velocity of the plane relative to air = [tex]V_{p}[/tex]

Velocity of the jet stream = [tex]V_{w}[/tex]

Velocity of the plane relative to ground = [tex]V_{g}[/tex]

Solution:

Note: Solution is given in the attachment. Please refer to the attachment for the sketch.

b. Express the velocity of the plane relative to the air as a vector.

Solution:

[tex]V_{p}[/tex] = |[tex]V_{p}[/tex]| cosФi + |[tex]V_{p}[/tex]| sinФj

where,

|[tex]V_{p}[/tex]| = magnitude of the vector.

|[tex]V_{p}[/tex]| =  525 MPH

Ф = 270° w.r.t to x - axis. (See the sketch in the attachment)

[tex]V_{p}[/tex] = |[tex]V_{p}[/tex]| cosФi + |[tex]V_{p}[/tex]| sinФj

Plug in the values into this equation to express it in the vector form as required.

[tex]V_{p}[/tex] = (525) cos270i + (525) sin270j

As, Cos270 = 0

and

Sin270 = -1

So,

[tex]V_{p}[/tex] = (525) (0)i + (525) (-1)j

[tex]V_{p}[/tex] = 0i -525j    

[tex]V_{p}[/tex] = (0,-525)  

c. Express the velocity of the jet stream as a vector.

Solution:

Velocity of the jet stream as a vector.

[tex]V_{w}[/tex] = |[tex]V_{w}[/tex]| cosФi + |[tex]V_{w}[/tex]| sinФj

where,

|[tex]V_{w}[/tex]| = magnitude of the vector.

|[tex]V_{p}[/tex]| =  120 MPH

Ф = 45°  (See the sketch in the attachment)

[tex]V_{w}[/tex] = |[tex]V_{w}[/tex]| cosФi + |[tex]V_{w}[/tex]| sinФj

Plug in the values into this equation to express it in the vector form as required.

[tex]V_{w}[/tex] = (120) cos45i + (120) sin45j

As, Cos45 = [tex]\frac{1}{\sqrt{2} }[/tex]

and

Sin45 =  [tex]\frac{1}{\sqrt{2} }[/tex]

So,

[tex]V_{w}[/tex] = (120) ([tex]\frac{1}{\sqrt{2} }[/tex])i + (120) ([tex]\frac{1}{\sqrt{2} }[/tex])j

[tex]V_{w}[/tex] = 60[tex]\sqrt{2}[/tex]i +60[tex]\sqrt{2}[/tex]j    

[tex]V_{w}[/tex] = ([tex]\sqrt{2}[/tex],[tex]\sqrt{2}[/tex])  

d. Find the velocity of the plane relative to the ground.

Solution:

Velocity of the plane relative to the ground = Sum of velocity of plane relative to the air and velocity of the jet stream

[tex]V_{g}[/tex] = [tex]V_{p}[/tex] + [tex]V_{w}[/tex]

[tex]V_{g}[/tex] = 0i -525j    +  60[tex]\sqrt{2}[/tex]i +60[tex]\sqrt{2}[/tex]j    

[tex]V_{g}[/tex] = 60[tex]\sqrt{2}[/tex]i + 60[tex]\sqrt{2}[/tex]  - 525j

[tex]V_{g}[/tex] = (60[tex]\sqrt{2}[/tex], 60[tex]\sqrt{2}[/tex]  - 525)

e. Find the actual speed and direction of the plane relative to the ground. Round to the  tenths.

Solution:

Actual Speed = |[tex]V_{g}[/tex]|  = magnitude of the velocity of the plane relative to the ground.

Actual Speed = |[tex]V_{g}[/tex]| = [tex]\sqrt{(60\sqrt{2}) ^{2} + (60\sqrt{2}-525) ^{2} }[/tex]

Actual Speed = |[tex]V_{g}[/tex]| = 448.3 MPH

Direction = Ф = [tex]tan^{-1}[/tex] ([tex]\frac{60\sqrt{2}-525 }{60\sqrt{2} }[/tex])

Direction = Ф = - 79.1°

To find out the direction with respect to x - axis.

Direction = Ф = 360 - 79.1

Direction = Ф = 280.9°

View image adnansoomro2019