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mcd173

  • 4 years ago

A skier (m=57.0 kg) starts sliding down from the top of a ski jump with negligible friction and takes off horizontally. If h = 6.20 m and D = 13.4 m, find H.

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  1. chand
    • 4 years ago
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    what is "h" ?

  2. chand
    • 4 years ago
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    Use the energy method. Decrease in potential energy= gain in kinetic energy mg(H-h) = 1/2 mv^2 here we get the velocity. After taking off, the range is given by R= u. t where "t" is the time of descent and 'u' is the velocity.

  3. chand
    • 4 years ago
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    Hope its clear

  4. hosein
    • 4 years ago
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    (1/2)mv^2=mgD so v=sqrt(2gD) v on above is v0 for next part of ask (when skier leave ski jump) y=(v0^2/2*g) so H=y+h

  5. chand
    • 4 years ago
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    isn't "d" the distance covered after he jumped?

  6. hosein
    • 4 years ago
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    i think D is ski jump's length

  7. hosein
    • 4 years ago
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    i drew above do you solve it?

  8. chand
    • 4 years ago
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    D should be the range i feel.

  9. chand
    • 4 years ago
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    Let us take D to be the range. Now, decrease in potential energy would be mg(H-h) as he came down a height of H-h So, mg(H-h) = 1/2 mv^2 v=(2g(H-h))^1/2

  10. hosein
    • 4 years ago
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    question want H did you get it?

  11. chand
    • 4 years ago
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    yes.

  12. hosein
    • 4 years ago
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    so it is...?

  13. chand
    • 4 years ago
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    approximately 15.026

  14. hosein
    • 4 years ago
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    how did you get time of descent

  15. chand
    • 4 years ago
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    t= {2h/g}^1/2

  16. hosein
    • 4 years ago
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    this t is time of H time of descent is: 2*t

  17. hosein
    • 4 years ago
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    how did you take v=u in two formula? mg(H-h) = 1/2 mv^2 R= u. t

  18. chand
    • 4 years ago
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    D= v. t where v= [2g(H-h)]^1/2 and t= [2h/g]^1/2 "t' is the time of descent from "h" to the ground. I typed u instead of v

  19. hosein
    • 4 years ago
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    u is velocity of body when it's arrive to ground but vis velocity in top of path

  20. hosein
    • 4 years ago
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    no i think you use 2*t in formula for D

  21. hosein
    • 4 years ago
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    hence d is all of horizontally path

  22. chand
    • 4 years ago
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    |dw:1331643793186:dw|

  23. chand
    • 4 years ago
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    "v' is the velocity of the man before taking off. We are not concerned about the velocity which he will have while landing on the ground

  24. chand
    • 4 years ago
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    Yes "D" is the horizontal distance covered.

  25. hosein
    • 4 years ago
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    did you see my diagram ? H is max height that man arrive . i didn't understand your fig

  26. hosein
    • 4 years ago
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    i mean that how did you yeild to u=v

  27. chand
    • 4 years ago
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    When a body takes off horizontally, the height from which it took off will be the maximum height. i took that the person slides from a height "H" and after reaching a height "h', he takes off and covers a horizontal distance 'D". I mistyped u or v.

  28. chand
    • 4 years ago
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    mistyped u for v

  29. chand
    • 4 years ago
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    am i clear?

  30. hosein
    • 4 years ago
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    yes you'r right

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