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calculusxy

  • one year ago

MEDAL!!!! If i'm driving in a car at 30kph and a friend is driving in a car with the same mass at 60kph, my friend's car's kinetic energy is bigger than mine by a factor of what? (that is, divide my friend's over mine.)

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  1. calculusxy
    • one year ago
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    @jim_thompson5910

  2. jim_thompson5910
    • one year ago
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    Hint: Kinetic Energy (KE) KE = (1/2)*m*v^2 m = mass v = velocity

  3. calculusxy
    • one year ago
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    well since it said that the masses are the same, it would eventually cancel out. however, the velocity would be different because one is going 60 kph and the other is going 30 kph. thus, would i do: \[\frac{ 60^2 }{ 30^2 } = \frac{ 3600 }{ 900 } = 4 ? \]

  4. jim_thompson5910
    • one year ago
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    correct, the friend has 4 times more KE

  5. calculusxy
    • one year ago
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    i just wanted to make sure what the units would be.

  6. calculusxy
    • one year ago
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    would it just be J , like 4J

  7. jim_thompson5910
    • one year ago
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    The joule units would cancel though

  8. calculusxy
    • one year ago
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    only 4 right?

  9. jim_thompson5910
    • one year ago
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    example: your car m = 100 v = 30 friends car m = 100 v = 60 ------------------------------------------------------- Your KE KE = (1/2)*m*v^2 KE = (1/2)*100*30^2 K = 45,000 Friends KE KE = (1/2)*m*v^2 KE = (1/2)*100*60^2 K = 180,000 Ratio of the two KE values 180,000/45,000 = 4 whatever the units for the KE were, they cancel out when you divide

  10. jim_thompson5910
    • one year ago
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    yeah only 4

  11. calculusxy
    • one year ago
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    okay thanks :)

  12. jim_thompson5910
    • one year ago
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    np

  13. calculusxy
    • one year ago
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    so there is also another question on the difference on potential and kinetic energy

  14. calculusxy
    • one year ago
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    @jim_thompson5910

  15. calculusxy
    • one year ago
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    i wrote: "potential energy is the amount of energy in an object when it is still and at a certain position, however, kinetic energy is when you're calculating the amount of energy of an object when it is moving."

  16. calculusxy
    • one year ago
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    will that be fine?

  17. jim_thompson5910
    • one year ago
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    potential energy (PE) is the amount of stored energy that can be used and converted into KE example: pick up a rock and place it on a ledge. It has PE stored up. When you push it off the ledge, it speeds up and hits the ground converting that PE into KE

  18. jim_thompson5910
    • one year ago
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    potential energy due to gravity PE = m*g*h

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