Relative Motion- Airplane/Wind

In summary, it takes 6.7 hours for a plane to fly from San Francisco to Chicago, an east-west flight of 2000 miles each way, if the wind is blowing at 120mph from the west to the east.
  • #1
revults
10
0

Homework Statement



A jetliner has a cruising air speed of 620mph relative to the air.

Part B
How long does it take this plane to fly round-trip from San Francisco to Chicago, an east–west flight of 2000 miles each way, if the wind is blowing at 120mph from the west to the east?

Homework Equations


The Attempt at a Solution



I've tried 8 hours.
and 7.225 hours.
 
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  • #2
Show us your work, or we can't tell where, if anywhere, you went astray.
 
  • #3
i did

620-120= 500

so that makes 4000/500= 8 hoursfor 1 other

it only affects 1 trip

so 2000/620= 3.225

2000/500= 4

so trip time = 7.225

both answers wrong
 
  • #4
The wind affects the trip in both directions: it helps in one direction and opposes in the other.
 
  • #5
620 + 120 one-way = 740
620 - 120 one-way = 500

2000/740 mph = 2.70
2000/500 mph = 4
= 6.7 hoursis that correct
 
  • #6
hi there, welcome to physicsforums. I'm guessing your assumption is that the wind velocity and cruising velocity 'add up' to get the true speed. Since they don't give you any other information, then this does seem like the right way to do it.

I get a different answer to you though. Remember that since he is doing a two-way flight, that on the way there, the plane is going against the wind, and with the wind on the way back.

EDIT: lol, I only saw your first post when I wrote this. And yes, I also get an answer of 6.7 hours
 
  • #7
BruceW said:
hi there, welcome to physicsforums. I'm guessing your assumption is that the wind velocity and cruising velocity 'add up' to get the true speed. Since they don't give you any other information, then this does seem like the right way to do it.

I get a different answer to you though. Remember that since he is doing a two-way flight, that on the way there, the plane is going against the wind, and with the wind on the way back.


I posted some new work, is that what you got?
 
  • #8
yep! nice work :)
 

Related to Relative Motion- Airplane/Wind

1. What is relative motion in relation to airplanes and wind?

Relative motion is the change in position of an object in relation to another object. In the context of airplanes and wind, it refers to the movement of the airplane in the air relative to the movement of the wind.

2. How does wind affect the speed and direction of an airplane?

Wind can either help or hinder the speed and direction of an airplane. If the wind is blowing in the same direction as the airplane, it can increase the speed of the airplane. However, if the wind is blowing in the opposite direction, it can decrease the speed and cause the airplane to drift off course.

3. What is the difference between airspeed and groundspeed?

Airspeed refers to the speed of the airplane relative to the air surrounding it. Groundspeed, on the other hand, refers to the speed of the airplane relative to the ground beneath it. The difference between these two speeds is caused by the effect of wind on the airplane.

4. How do pilots account for wind when flying?

Pilots use a variety of instruments and techniques to account for wind when flying. They may use a wind correction angle, which involves adjusting the heading of the airplane to compensate for the effect of wind. They may also use a navigational tool called a wind triangle to calculate the effect of wind on their flight path.

5. Can wind affect the altitude of an airplane?

Yes, wind can affect the altitude of an airplane. Strong headwinds can increase the lift on the wings and cause the airplane to climb, while strong tailwinds can decrease the lift and cause the airplane to descend. Pilots must be aware of wind conditions and make adjustments to maintain a safe and stable altitude.

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