Conservative forces and Mechanical Energy

  • Thread starter bjudia
  • Start date
  • #1
bjudia
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1. A 750-kg automobile is moving at 20.0 m/s at a height
of 5.0 m above the bottom of a hill when it runs out of
gasoline. The car coasts down the hill and then continues
coasting up the other side until it comes to rest.
Ignoring frictional forces and air resistance, what is the
value of h, the highest position the car reaches above
the bottom of the hill?a




2. E1=E2 or K1 + U1 = K2 + U2



3. 1/2mv2+mgy=1/2mv2+mgy

1/2(750kg)(20m/s)2+(750kg)(9.8m/s2)(5m)=1/2(750kg)(0m/s)2+(750kg)(9.8m/s2)(Y)

I got y=25.41m or 25m with correct sig figs is that correct?
 

Answers and Replies

  • #2
BruceW
Homework Helper
3,611
121
looks good to me. nice work. You could put in another sig fig in your answer, but I guess it can't be bad to over-estimate the error.
 

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