Find the Optimal Starting Time for a Tied Race in Physics Kinematics

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Discussion Overview

The discussion centers around determining the optimal starting time for one runner in a kinematics problem involving a tied race. Participants explore the relationships between the speeds of two runners, the distance they must cover, and the time delay for one runner.

Discussion Character

  • Mathematical reasoning

Main Points Raised

  • John runs at 5 m/s and Joe runs at 3 m/s over a distance of 300 m, with John starting t seconds after Joe.
  • One participant proposes the equation \(5T = 3(T + t)\) to relate the times and speeds of the runners.
  • Another participant suggests that the equation simplifies to \(2T = t\), leading to a calculation of \(t = 120\) seconds.
  • A correction is made regarding the distribution of terms in the equation, indicating that it should be \(5T - 3T = 3t\).
  • Substituting \(T = 60\) seconds into the corrected equation leads to \(t = 40\) seconds, with a distance of 120 m for Joe.
  • Participants express uncertainty about their calculations and seek confirmation of their results.

Areas of Agreement / Disagreement

There is some agreement on the final value of \(t = 40\) seconds, but earlier calculations and interpretations of the equations show some discrepancies and uncertainty among participants.

Contextual Notes

Participants rely on specific assumptions about the runners' speeds and the total distance, but there may be unresolved steps in their mathematical reasoning.

leprofece
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John runs at 5 m/s joe runs at 3m/seg the distance to run is 300 m Antony in order to do the race more exciting allows john start t seconds after joe What is the t value so that the race finishes in a tie?? what distance was allowed to joe?? Answer 40 seg and 120 m

I don't know how to denote the time of john
5t = 3 (300-t) ?'
 
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Let's let $T$ represent the time John runs, and so $T+t$ is the time Joe runs. We know the must both run 300 m during their respective times, and so we may write:

$$5T=3(T+t)$$

$$5T=300\implies T=60$$

Can you proceed?
 
sure 5T -3T = t
2 T = t
t = 2 *60 = 120
please I am not Sure cooecte me if I am not correct
and thanks for you reply greetings and regards
 
You should have:

$$5T-3T=3t$$

You didn't distribute the $3$ before...:D
 
2T = 3t

2(60) = 3t
so t = 40 seg

Ok and now: 3 (40) = 120 m

ithink i am ruight now do I?
 
leprofece said:
2T = 3t

2(60) = 3t
so t = 40 seg

Ok and now: 3 (40) = 120 m

ithink i am ruight now do I?

Yes, that's correct! (Sun)
 

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