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Motion in one dimension help?

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An automobile which travels with the constant speed 20 m/s passes in a section in the moment t=0s and 5 seconds later in the same section passes another automobile which travles with the speed of 30 m/s in the same direction.a) Find when the second car meets the first one.
My solution : x1=x2 20t=30(t-5) and here we find t=15 seconds.b) Whats the distance between the cars since the section until they meet? How to do this one? Just give me an idea..
 

tiny-tim

Science Advisor
Homework Helper
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Hi Elaia06! :smile:

hmm :confused:

ahh! o:), i think you mean …​
An automobile which travels with the constant speed 20 m/s passes a line at time t=0s and 5 seconds later another automobile which travels with the speed of 30 m/s in the same direction passes the same line.
a) Find when the second car meets the first one.
My solution : x1=x2 20t=30(t-5) and here we find t=15 seconds.b) Whats the distance past the line when they meet?
your equations should be …
x1 = 20t
x2 = 30(t-5)
x1 = x2 :wink:

you already have t = 15,

so x1 = x2 = … ? :smile:
 
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I did it this way, but my teacher said it was not correct o_O Now I logged in physicsforum and I see we have the same opinion :S Even the other students had done it this way.Whatever,thank you :)
 

tiny-tim

Science Advisor
Homework Helper
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Hi Elaia06! :smile:

Please remember that I rewrote the question so that it fitted your solution!

Perhaps the question means something different?
 
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So the distance question means " The two cars,since they pass the line have a distance.They keep this distance until they meet.Find the distance.This is basically what I did,found that distance.
 

tiny-tim

Science Advisor
Homework Helper
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" The two cars,since they pass the line have a distance.They keep this distance until they meet.Find the distance.
sorry, but that doesn't make any sense :redface:

(how can they keep the distance if the distance is getting smaller?)
 
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Thats what it says in my book,literally.I am not english and the book I work with is translated poorly ..Whatever,thank you anyway..
 

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