race on rounded way

shahar

shahar

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two people running with the same speed on a circular track that is 200 m in opposite direction, they want to meet in the point that is opposite to the starting point (on the circle).
How can I calculate the time that pass after the beginning of the running?
 
shahar said:
two people running with the same speed on a circular track that is 200 m in opposite direction, they want to meet in the point that is opposite to the starting point (on the circle).
How can I calculate the time that pass after the beginning of the running?
Click to expand...
If you knew how fast they are running, you could do this by observing how far each has to run.

But as it is, there is no information pertaining to time or speed.
 
Dr.Peterson said:
If you knew how fast they are running, you could do this by observing how far each has to run.

But as it is, there is no information pertaining to time or speed.
Click to expand...
they have the same speed. Isn't this enough?
 
shahar said:
they have the same speed. Isn't this enough?
Click to expand...
Because they are running at the same average speed, you know where they will meet, but you cannot determine when they will meet.

[MATH]r = \dfrac{d}{t} \implies t = \dfrac{d}{r}.[/MATH]
To get a numeric answer for t, you need the values of d and r.
 
Last edited:
shahar said:
they have the same speed. Isn't this enough?
Click to expand...
Each runs 100 meters. If they run at 100 m/s, it will take 1 second. If they run at 10 m/s, it will take 10 seconds. If they run at 1 m/s, it will take 100 seconds. And so on.

Do you not see that? If the units in the data don't include any time (as in seconds or meters per second or kilometers per hour), then you can't get a time out of it.

shahar said:
what is d? And I think formula is the solution.
Click to expand...
d means distance, which in this case is 100 meters.

Are you saying the problem is not asking for a number, but a function of (not specified) speed? Then it should say so.
 
O.K, Now it clear. The writer miss the unit. Now I know why it in the draft page.

Thanks.
 
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