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Kinematic Equations

  • Thread starter 7yler
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  • #1
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A person runs 100 m in 9.77 s. Maximum speed was reached in 3 s, then maintained for the rest of the time. What was the acceleration during the first 3 seconds?

I know that I can find the average velocity, which is 100 m/9.77 s, and i know that initial velocity is 0 m/s. I don't know how to find the acceleration because I don't know what the velocity is. Could anyone guide me through the methodology of this problem? I don't want the numerical answer.
 

Answers and Replies

  • #2
it can be like this.
initial velocity=0
velocity at the end of 3 sec is100/9.77m/s i.e. 10.23m/s
now acc. = (final vel. - initial vel.)/time=(10.23-0)/3=3.41m/sec.sq
so,acc. after 3 sec is 3.41m/sec.sq
 
  • #3
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The system is telling me that that is incorrect.
 
  • #4
verty
Homework Helper
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Find the displacement and velocity at 3 seconds. Find the displacement and velocity at 9.77 seconds.
 
  • #5
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How do I find displacement and velocity if I don't know acceleration?
 
  • #6
verty
Homework Helper
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I meant, find equations for them (the equations will contain "a").
 
  • #7
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I don't understand how I can solve the equations with two missing variables.
 

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