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mayankdevnani

  • 3 years ago

A body of mass 2 kg is thrown up vertically with a kinetic energy of 490 J.If the acceleration due to gravity is 9.8 m/s^2, the height at which the kinetic energy of the body becomes half of the original value is - a) 50 m b) 25 m c) 12.5 m d) 10 m

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  1. mayankdevnani
    • 3 years ago
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    @Hero @hartnn @Chlorophyll @robtobey @sauravshakya @kropot72 @jiteshmeghwal9 @hba

  2. mayankdevnani
    • 3 years ago
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    @mathslover have a look:)

  3. mathslover
    • 3 years ago
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    First find the original value ... what you get?

  4. mayankdevnani
    • 3 years ago
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    original value????

  5. mathslover
    • 3 years ago
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    sorry i think it is given

  6. sauravshakya
    • 3 years ago
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    Potential energy of the body =mgh

  7. sauravshakya
    • 3 years ago
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    u know it?

  8. mayankdevnani
    • 3 years ago
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    ok!!

  9. mayankdevnani
    • 3 years ago
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    yaa

  10. mathslover
    • 3 years ago
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    490 J = KE (ORIGINAL)

  11. mayankdevnani
    • 3 years ago
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    yaa

  12. mathslover
    • 3 years ago
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    half of it will be 490 /2 J = 245 J , correct?

  13. mayankdevnani
    • 3 years ago
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    why you do the half the K.E @mathslover

  14. mathslover
    • 3 years ago
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    @mayankdevnani because we have to find the height when the new kinetic energy equals half of the original one. ...

  15. mayankdevnani
    • 3 years ago
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    @03225186213

  16. mathslover
    • 3 years ago
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    therefore the new kinetic energy must be equal to 245 Joules.

  17. mayankdevnani
    • 3 years ago
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    yaa

  18. mayankdevnani
    • 3 years ago
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    correct!!!

  19. mathslover
    • 3 years ago
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    therefore we have : 1/2 m v^2 = 245 J 1/2 m (u^2 + 2gh ) = 245 J 1/2 m (2gh) = 245 mgh = 245 J 2 kg * 9.8 * h = 245

  20. mathslover
    • 3 years ago
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    solve for h and you will get h = 12.5 m

  21. mayankdevnani
    • 3 years ago
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    1/2 m (u^2 + 2gh ) = 245 J ??????????????

  22. mathslover
    • 3 years ago
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    got it?

  23. mayankdevnani
    • 3 years ago
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    no!!!!

  24. mayankdevnani
    • 3 years ago
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    1/2 m (u^2 + 2gh ) = 245 J this line!!!

  25. mathslover
    • 3 years ago
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    since v^2 = u^2 + 2gh therefore..

  26. mayankdevnani
    • 3 years ago
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    ok

  27. mayankdevnani
    • 3 years ago
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    thnx.... i got it @mathslover

  28. mathslover
    • 3 years ago
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    good,...

  29. mayankdevnani
    • 3 years ago
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    let @03225186213 be answer.... plz wait

  30. 03225186213
    • 3 years ago
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    1/2 mv^2=mgh 490/2=2 (-9.8)h h= -9.8 because it is moving against gravity

  31. mathslover
    • 3 years ago
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    @03225186213 same I thought BUT it is given in the quest. that g = 9.8 m/s^2

  32. mayankdevnani
    • 3 years ago
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    yaaa you are correct thnx @mathslover and @03225186213

  33. 03225186213
    • 3 years ago
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    welcome

  34. mayankdevnani
    • 3 years ago
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    :)

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