Find Maximum Speed of Athlete in 100m Sprint - Solve with Integration

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Discussion Overview

The discussion revolves around determining the maximum speed of an athlete in a 100-meter sprint, focusing on the application of kinematics and integration due to the athlete's changing acceleration. The problem involves analyzing motion with constant acceleration followed by constant velocity.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant proposes using integration to solve for maximum speed due to the non-constant motion of the athlete.
  • Another participant argues that calculus is unnecessary, suggesting the use of kinematic equations since the athlete's acceleration is constant during the initial phase.
  • A participant expresses uncertainty about the acceleration, noting the lack of information regarding displacement during the latter part of the sprint.
  • One participant suggests visualizing the problem with a velocity-time graph, indicating that the area under the graph represents distance and can help find the velocity.
  • A later reply confirms that the proposed approach of using the velocity-time graph was successful in aiding understanding.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the necessity of calculus in solving the problem, with some advocating for kinematic equations while others support the use of integration. The discussion remains unresolved on the best approach to take.

Contextual Notes

There are limitations regarding the assumptions made about the athlete's motion, particularly concerning the unknown acceleration and displacement during the latter part of the sprint. The discussion does not resolve these uncertainties.

Who May Find This Useful

This discussion may be useful for students or individuals interested in kinematics, particularly in understanding the application of different mathematical approaches to motion problems.

Junkwisch
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In a 100 metre sprint, an athlete reaches her maximum speed in 3.0 seconds, starting from rest, assuming constant acceleration. She maintains her maximum speed until the finish, with an overall time of 11.0 seconds. Determine her maximum speed, vmax.


I'm trying to solve this problem but it is with little successes, I realized that this is not a constant motion (she stop accelerating). Thus I have to solve it with some kind of integration. Can anyone tell me what equation do I have to use?
 
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No, you don't need calculus here. Her acceleration was constant and she reached the maximum speed in 3 seconds and covered a distance of 100m.
You can use the kinematics equation involving final velocity, initial velocity, distance and time
 
But I don't know what her acceleration is, even though it is constant for the first three seconds. Since I do not know her displacement in the last eight seconds.
 
Junkwisch said:
But I don't know what her acceleration is, even though it is constant for the first three seconds. Since I do not know her displacement in the last eight seconds.
Oh, I think I misinterpreted the question. What you can do is draw a sketch of the velocity time graph. You don't know the velocity so leave the y-axis empty. Since the area under the graph is the distance , you can find the velocity.
It should be in a trapezium shape.
 
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Thankyou so much adjacent, it worked :D
 
You are welcome :smile:
 

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