Minkowski diagram, where to put an event

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SUMMARY

The discussion centers on the application of the Minkowski diagram to analyze the interaction between two cars, A and B, with a light signal sent from B to A. The participants clarify that the light signal, sent at t = - (1/3) ms from a distance of 300 km, does not reach car A because the calculated ratio of the distances indicates the event is outside the light cone. The conclusion is that the event is not inside the light cone, confirming that the light signal will not reach car A.

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Redwaves
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Homework Statement
At t=0 A is moving
At t = -1/3 ms B is at 300km north and send a light beam
Draw the Minkowski diagram then tell if the light beam will reach A
Relevant Equations
##-\frac{1}{3} ms = -\frac{10^{-3}}{3}s##
##300km = 3\cdot10^5 m##
##ct = -\frac{10^{-3}}{3}s \cdot c##
I drew the Minkowski diagram, but I'm not sure if this is correct.
From what I drew the angle between x and ct ##\approx 0##
then the event is "inside" the light ray and will eventually reach A.
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Is there any relative velocity between A and B, and if so, how much?
 
Chestermiller said:
Is there any relative velocity between A and B, and if so, how much?
No, that's all I have
 
Redwaves said:
No, that's all I have
Well, it seems like there is something missing from the problem statement. What is the exact wording?
 
Chestermiller said:
Well, it seems like there is something missing from the problem statement. What is the exact wording?
The statement is in french, here is the google translate.

A and B are two cars At t = 0, car A starts to move forward. B sent a light signal to try
to warn him: B is 300 km to the North and sends his signal at t = - (1/3) ms;

I have to draw the world line of that light signal
I'm wondering if I should have draw the cone of light instead of the diagram above?

Thus, since opposite/adjacent < 1, the event in inside the cone of light and if the event in inside the cone of light, the light signal will eventually reach A. Is it correct?

Edit: Since ##ct = 300000000 \cdot -\frac{10^{-3}}{3} = 100000m##
And ##100000/300000 < 1## this is not inside the cone of light, so it will not reach A.
 
Last edited:
Redwaves said:
The statement is in french, here is the google translate.

A and B are two cars At t = 0, car A starts to move forward. B sent a light signal to try
to warn him: B is 300 km to the North and sends his signal at t = - (1/3) ms;

I have to draw the world line of that light signal
I'm wondering if I should have draw the cone of light instead of the diagram above?

Thus, since opposite/adjacent < 1, the event in inside the cone of light and if the event in inside the cone of light, the light signal will eventually reach A. Is it correct?

Edit: Since ##ct = 300000000 \cdot -\frac{10^{-3}}{3} = 100000m##
And ##100000/300000 < 1## this is not inside the cone of light, so it will not reach A.
Any information on the speed with which car A starts to move forward?
 
Chestermiller said:
Any information on the speed with which car A starts to move forward?
That's all I have.
 

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