Acceleration problem. me vs book

  • Thread starter Rhine720
  • Start date
  • #1
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Homework Statement


A bus is traveling at 30.0 km/h speeds up at a constant rate of 3.5 ms/^2. What velocity does it reach at 6.8 seconds later?

book says 120.km/hour
I get 115 km/hour

Homework Equations


Vf=Vi+a x delta t


The Attempt at a Solution


First I changed 30.0 km/hour to 30000 m/3600s then reduced to 8.3 m/s. Used formula to get Vf=32.13m/s

I divide 32.13 by 1000 to get .03213 km/s then 1.9278 km/m then 115.668 km/h.

I've worked this problem a hundred different ways and get the same answer. AM i right or the book?
 

Answers and Replies

  • #2
Looks like you and the book are correct. I would assume that the book is answering the question to 2 significant figures, thus 115.668km/h is 120km/h assuming your math is correct.
 
  • #3
88
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oh my goodness i forgot all about sig figs. Thank you very much
 
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