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Bike on a hill

  • Thread starter Aikenfan
  • Start date
  • #1
48
0

Homework Statement


I wasn't sure if i was doing this problem correctly, if anyone could double check for me, that would be great!
You ride your bicycle down a hill. Your total mass is 40 kg. At the top of the hill, your
speed is 5 m/s. The hill is 20 m high and 200 m long. If the force of friction is 20 N, what is
your speed at the bottom of the hill?






Homework Equations





The Attempt at a Solution


Top =
KE = 1/2 m v ^2
KE = 1/2 (40) (5)^2 = 500

PE = mgh
(40) (9.8) (20) = 7840

W = Fd
(20)(200)= 4000

7840 - 4000
=3840

3840 + 500 = 4340 = 1/2 (40) v ^2
divide both sides by 20
take the square root, and got 14.7 as my answer...
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
26,258
618
Looks ok to me. Though I'd be more careful about putting units on things.
 
Last edited:

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