Is relative velocity confusing in multiple vector systems?

In summary, the conversation discusses the correct resolution of vectors and the confusion regarding the relationship between ##\alpha## and ##\beta##. It is determined that the diagram is incorrect and the correct method is to transport the V(woman) vector to the right and construct the sum with the end of V(woman) at the tip of V(rain). The conversation also touches on the concept of relative velocity, which can be confusing.
  • #1
Hijaz Aslam
66
1
SQGAh3H.png


Are the vectors resolved correctly? I get a different answer to this question(well my diagram itself is different). How can ##\beta## be greater than ##\alpha##?

Isn't it that here ##\alpha## should be in place of ##\beta## and ##\beta## in place of ##\alpha## and both ##V(rain,woman)## and ##V(rain)## should be in each others place?
 
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  • #2
I believe that the diagram is wrong. The V(woman) vector should be transported to the right, starting at the tip of V(rain), and the sum should be constructed putting the end of V(woman) at the tip of V(rain). As the vectors of the picture seem to be to scale, the sum vector will lean to the right, clearly...
 
  • #3
The speed of the rain in respect to ground vg is given by
v_g=v_rw+v_w

where v_rw is the speed of the rain in respect to the woman and v_w is the speed of the woman.
Take these as velocities (vectors) and this is what they have there.

If the woman runs against the rain, the horizontal component of the rain's velocity should be larger from the point of view of the woman than from the ground. The vertical component is not changed. So the angle is larger.
 
  • #4
nasu said:
The speed of the rain in respect to ground vg is given by
v_g=v_rw+v_w

where v_rw is the speed of the rain in respect to the woman and v_w is the speed of the woman.
Take these as velocities (vectors) and this is what they have there.

If the woman runs against the rain, the horizontal component of the rain's velocity should be larger from the point of view of the woman than from the ground. The vertical component is not changed. So the angle is larger.

Yes, I was wrong in my post above... Imagining the rain falling vertically, running in any direction will result in the angle perceived by the runner growing more and more horizontal the faster he runs...
 
  • #5
nasu said:
The speed of the rain in respect to ground vg is given by
v_g=v_rw+v_w

where v_rw is the speed of the rain in respect to the woman and v_w is the speed of the woman.
Take these as velocities (vectors) and this is what they have there.

If the woman runs against the rain, the horizontal component of the rain's velocity should be larger from the point of view of the woman than from the ground. The vertical component is not changed. So the angle is larger.
Oh yes. This relative velocity baffles me always :(

Nasu - thanks for your reply. Your answer cleared it. If you don't mind can you look into this problem in my thread ( https://www.physicsforums.com/threa...taining-multiple-vectors.777125/#post-4887266 ) Relative velocity catches me there too :( .
 

1. What is relative velocity of rain?

The relative velocity of rain is the speed at which rain appears to be falling from a stationary observer's perspective. It takes into account both the actual velocity of the raindrops and the observer's own motion.

2. How is relative velocity of rain calculated?

The relative velocity of rain can be calculated using vector addition. First, the actual velocity of the raindrops is determined using weather instruments such as Doppler radar. Then, the observer's own velocity is factored in to determine the relative velocity.

3. Does the relative velocity of rain affect its impact?

Yes, the relative velocity of rain can affect its impact. If the observer is moving towards the direction of the rain, the relative velocity will be higher and the raindrops may hit with more force. On the other hand, if the observer is moving away from the rain, the relative velocity will be lower and the raindrops may hit with less force.

4. How does wind affect the relative velocity of rain?

Wind can greatly affect the relative velocity of rain. If the wind is blowing in the same direction as the rain, it can increase the relative velocity and cause the rain to fall at a steeper angle. If the wind is blowing in the opposite direction, it can decrease the relative velocity and cause the rain to fall at a shallower angle.

5. Is the relative velocity of rain constant?

No, the relative velocity of rain is not constant. It can vary depending on the speed and direction of the observer's motion, as well as the wind conditions. Changes in altitude can also affect the relative velocity of rain. However, the actual velocity of the raindrops may remain relatively constant.

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