Bicycle coasting up a Hill

  • #1

Homework Statement



Coasting along at 7.10 m/s, a 60.0 kg bicyclist on a 7.60 kg bicycle encounters a small hill. If the speed of the bicyclist is 6.00 m/s at the top of the hill, how much work was done on the bicyclist and her bike?


Homework Equations



KEf-KEi=W
.5mvi^2-.5mvf^2
kg*m^2*s^-2
m=60kg+7.60kg
v=m/s


The Attempt at a Solution



I tried finding the loss in KE and having that be the work done. I get

.5mVf^2 -.5mVi^2
.5*67.6kg*36 - .5*67.6kg*50.41

I get -487 J and it tells me this is the wrong answer? What did I do wrong?
 
Last edited:

Answers and Replies

  • #2
berkeman
Mentor
59,069
9,167
Please write out the whole equations. Include the mass and the units.
 
  • #3
261
2
I tried finding the loss in KE and having that be the work done. I get

.5m(Vf-Vi)^2 and I get -487 J and it tells me this is the wrong answer? What did I do wrong?
Your final expression is incorrect mathematically.
 
  • #4
I relized i posted that wrong but the answer comes out to -487 the right way but thats the wrong answer. I edited and wrote everything out.
 

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