Problems involving frames of reference and relative velocity

In summary, the first question involves determining the velocity of a small plane relative to the ground when faced with a crosswind. The second question asks which of two kayakers will reach the other side of a river first when one is angled upstream and the other is going straight across. The third question involves finding the velocity of a plane relative to the air when flying from London to Rome with a crosswind. The key concept for all three questions is vector addition, and drawing diagrams can be helpful in visualizing the relationships between angles and magnitudes in these situations.
  • #1
Byrgg
335
0
I have a few questions here, and I'm stuck/confused on some of them. Here they are:

1. The air speed of a small plane is 215 km/h.The wind is blowing at 57 km/h from the west. Determine the velocity of the plane relative to the ground if the pilot keeps the plane aimed in the direction [34 degrees E of N].

I'm not really sure about this one, it seems a little different from the examples the teacher showed us in class. I'm not really sure which angle the angle mentioned is referring to, basically, I just need help figuring out how to set up the problem, and then I should be able to continue without problems from there(I hope).

2. Two kayakers can move at the same speed in calm water. One begins kayaking straight across a river, while the other kayaks at an angle upstream in the same river to land straight across from the starting position. Assume the speed of the kayakers is greater than the speed of the river current. Which kayaker reaches the far side first? Explain why.

I don't really know how to figure this out. You have one who is angled so that they partially face upstream, and then one trying to go straight ahead, but the river will alter their direction, so they'll be angled facing downstream. Which gets there first? I don't know, they are both traveling at the same speed(I'm assuming), but in different directions. I'm a little confused about this whole thing, any help here would be appreciated.

3. A pilot is required to fly directly from London, UK, to Rome, Italy in 3.5 h. The displacement is 1.4 x 10^3 hm [43 degrees E of S]. A wind is blowing with a velocity of 75 km/h [E]. Determine the required velocity of the plane relative to the air.

For this one, I got pretty far, and it seems as though I got the magnitude of the velocity right(it matched the answer in the back of the book), but my angle seemed off. If someone could help me figure out the proper way to figure out the angle, then I'd be greatful. If you want me to show the work that I've done, or make a diagram, I'll try to do so(mind you, the diagram may be hard for me to draw accurately, it will just be approximate).
 
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  • #2
Draw pictures, lable all of the quanities, then use what you should know about vector addition. Your drawings do not need to be precise, just good enough to show the relationships. Lable angles and magnetudes, break them down into components and add 'em up.
 
  • #3
That applies for all of these situations, right? I didn't really know how to draw the diagram for the first one, and the second I found hard to work with in general.
 
  • #4
Could some one give me some more help please? I'm still confused about these questions.
 

What is a frame of reference?

A frame of reference is a set of coordinate axes, points, and lines used to define the position and orientation of an object or event in space and time. It serves as a standard for measuring and describing the motion and interactions of objects within it.

How does relative velocity differ from absolute velocity?

Relative velocity is the measure of the velocity of an object in relation to another object or frame of reference. It takes into account the motion of both objects and their respective frames of reference. Absolute velocity, on the other hand, is the measure of an object's velocity in relation to a fixed point or absolute frame of reference.

What are some common problems involving frames of reference and relative velocity?

Some common problems involving frames of reference and relative velocity include calculating the velocity of an object in motion relative to another object or frame of reference, determining the relative positions of objects at different points in time, and predicting the future motion of an object based on its current velocity and frame of reference.

How can frames of reference and relative velocity be used to understand motion?

Frames of reference and relative velocity are crucial concepts in understanding motion because they allow us to describe and measure the movement of objects in relation to other objects or frames of reference. By using these concepts, we can accurately predict and analyze the motion of objects in various scenarios.

What is the difference between an inertial frame of reference and a non-inertial frame of reference?

An inertial frame of reference is a frame of reference in which Newton's first law of motion holds true, meaning that an object at rest will remain at rest and an object in motion will continue to move at a constant velocity unless acted upon by an external force. A non-inertial frame of reference, on the other hand, is one in which the laws of motion do not hold true, such as a frame of reference that is accelerating or rotating.

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