Help Needed! Deceleration! Quick Please!

  • Thread starter Masschaos
  • Start date
  • #1
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1. I need to find the deceleration of a bicycle, I have Finial velocity at 0, initial velocity at 5.56m/s and discplacement at 1.80m



2. V^2+U^2/(2*S)=A
not sure if formula is correct



The Attempt at a Solution


I find that 0^2+5.56^2/(2*180) = -27m/s/s
Is this correct? i think its too fast
 

Answers and Replies

  • #2
Doc Al
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I find that 0^2+5.56^2/(2*180) = -27m/s/s
Is this correct? i think its too fast
Redo your arithmetic.
 
  • #3
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(v^2-u^2)/(2*s)=a

(0^2-5.56^2)/(2*1.8m) = -27m/s/s

... is that better?
Is the formula incorrect?
 
  • #4
tiny-tim
Science Advisor
Homework Helper
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Welcome to PF!

Hi Masschaos! Welcome to PF! :smile:

(try using the X2 tag just above the Reply box :wink:)
I find that 0^2+5.56^2/(2*180) = -27m/s/s
Is this correct? i think its too fast
Your formula (a = -u2/2s) is correct, but your arithmetic isn't …

did you multiply by 1.8 instead of dividing? :confused:

(you don't seem very good at using brackets)
 
  • #5
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Thanks! its late at night here and i was stressing because i thought i had the wrong formula for my assignment... thanks for the heads up

So what i should do is (v2-u2)/2*1.8)?
 
  • #6
Doc Al
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So what i should do is (v2-u2)/2*1.8)?
Yes. The formula is a = (v2 - u2)/(2*s), not ((v2 - u2)/2)*s (which is what you seemed to be doing). I suspect you are just being sloppy with your calculator.
 

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