2D Relative Velocity, Two Planes

In summary: The second step is to identify the direction of the vector that has the largest magnitude. In this problem, that vector is the velocity vector of plane 1 (v1) relative to plane 2. This vector is pointing in the direction of 9.8 m/s.In summary, the velocity of plane 1 is greater than the velocity of plane 2.
  • #1
JKLS
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Homework Statement



Two airplanes taxi as they approach the terminal. Plane 1 taxies with a speed of 11 m/s due north. Plane 2 taxies with a speed of 8.5 m/s in a direction 20 degrees north of west.

a) What is the magnitude of the velocity of plane 1 relative to plane 2?
b) What is the direction of the velocity of plane 1 relative to plane 2? (in degrees North of East)
c) What is the magnitude of the velocity of plane 2 relative to plane 1?
d) What is the direction of the velocity of plane 2 relative to plane 1? (in degrees South of West)

Homework Equations



The Attempt at a Solution



My main problem here is the setup of the question, as in, where the vectors are placed in reference to one another. The final answers for any of the velocity magnitudes or directions are not provided in the textbook, nor has my professor been willing to meet with me. Also, the question is worded really stupidly.

So, my thinking so far:

The velocities of the two resultant vectors will have the same magnitude, and opposite direction. The vectors aren't merely added, since the addition of these vectors would not result in a vector with a direction in degrees North of East (in its "simplest form"). I attempted to subtract the vector v2 (velocity plane 2) from v1 (velocity plane 1) but the result wasn't accepted by my school's assignment module as correct (~13.5 m/s).

Any ideas?
 
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  • #2
If anyone can help me with the position of these vectors in relation to one another, and what the question is actually asking, that's all the help I need. The math is super easy, and I can manage questions labeled as much harder than this one fairly quickly. I just need help understanding what this question is asking, and how to set up the vector relationships. Thank you.
 
  • #3
I'd still love some help with this one. Just an idea on the setup is necessary... the wording is terrible.
 
  • #4
Hello - can someone offer some insight into how to approach this problem? Thank you.
 
  • #5
Vectors are "translated" to the origin for comparison.

The first step in such problems is to draw a diagram of the vectors involved. Here you go:

attachment.php?attachmentid=39518&stc=1&d=1317571047.gif
 

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1. What is 2D relative velocity?

2D relative velocity is a concept in physics that describes the motion of an object in two dimensions (usually represented by x and y axes) in relation to another object. It takes into account the velocity of both objects as well as their direction of motion.

2. How is 2D relative velocity calculated?

To calculate 2D relative velocity, we use vector addition. This means that we add the x and y components of the velocities of both objects to find the resultant velocity. The magnitude of the resultant velocity can be found using the Pythagorean theorem.

3. What is the difference between 2D and 3D relative velocity?

2D relative velocity only takes into account the motion of objects in two dimensions, while 3D relative velocity takes into account the motion in three dimensions (x, y, and z axes). This means that 3D relative velocity is more complex and requires vector addition in three dimensions.

4. How is relative velocity used in real-life situations?

Relative velocity is used in various fields, such as navigation, astronomy, and aviation. For example, pilots use relative velocity to calculate their speed and direction of motion in relation to other objects, such as other planes or landmarks.

5. Can relative velocity be negative?

Yes, relative velocity can be negative. This indicates that the objects are moving in opposite directions. The magnitude of the negative relative velocity is the difference between the velocities of the two objects.

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