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Q69E

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College Physics (Urone)
Found in: Page 125

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Short Answer

Unreasonable Results A commercial airplane has an air speed of m/s due east and flies with a strong tailwind. It travels km in a direction south of east in h.

(a) What was the velocity of the plane relative to the ground?

(b) Calculate the magnitude and direction of the tailwind’s velocity.

(c) What is unreasonable about both of these velocities?

(d) Which premise is unreasonable?

a. 556 msm/s.

b. 278 msAnd 10.0° SE .

c. The air speed is very high at m/s, which is more than the speed of sound. The wind speed is also very high at m/s. Hence the problem is unreasonable.

d. Either the distance is larger or the time calculated is smaller.

See the step by step solution

Step by Step Solution

Step 1: Definition of velocity

Velocity is the rate of change in position of an item in motion as seen from a specific frame of reference and measured by a specific time standard.

Step 2: The velocity of the plane relative to the earth

The speed of the plane relative to the ground is

V=dtV=3000 km1.5 hrV=2000 kmhr

Velocity in meter

V=2000×36001000V=556 ms

The speed of the plane relative to the earth is 556 m/s.

Step 3: Velocity of the air relative to the earth

Hence the velocity can be calculated by the following equation:

Vae=Vap+Vpe

The component table will be as below:

X

Y

Vap

-280

0

Vpe

554

-48.5

Resultant

274

-48.5

Here we need to find the x component and the y component.

X componentVpex=VicosθVpex=556cos5°Vpex=554

Y componentVpey=VisinθVpey=-556sin5°Vpey=-48.5

Step 4: Determine the resultant velocity

Hence the resultant vector will be

R=X2+Y2R=2742+-48.52R=278 ms

The velocity of the air relative to the earth is 278ms .

The direction of the velocity will be:

tanθ=YXtanθ=48.5274θ=10.0°

The resultant vector has the direction of 10.0° S E .

c) The airspeed is very high at 556m/s, which is more than the speed of sound. The wind speed is also very high at 276m/s. Hence the problem is unreasonable.

d) The distance may be larger, or the time calculated be smaller.

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