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GrizzlyChicken Group Title

The position of a mass on a spring (relative to equilibrium) at time t <= 0 is x(t) = 2 cos((pi)t) where x is in centimeters and t is in seconds. Answer the ques- tions. Include units! (a) What is the initial position of the mass? (b) What is the initial velocity of the mass? (c) What is the initial acceleration of the mass? (d) Does the mass initially move towards the wall or away from it? (e) At what point does the mass rst turn around?

  • 2 years ago
  • 2 years ago

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  1. goformit100 Group Title
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    post the question in physics section Not here @GrizzlyChicken

    • 2 years ago
  2. GrizzlyChicken Group Title
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    its in my calc book, isn't this math?

    • 2 years ago
  3. nphuongsun93 Group Title
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    a) put t = 0 and solve for x b) find x' and put t = 0 and solve for x' c) find x'' and put y = 0 and solve for x''

    • 2 years ago
  4. nphuongsun93 Group Title
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    it's both physics and math lol

    • 2 years ago
  5. nphuongsun93 Group Title
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    *typo fix* sorry c) find x'' and put t=0

    • 2 years ago
  6. GrizzlyChicken Group Title
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    wait, its x(t)=2cos((pi)(t))

    • 2 years ago
  7. GrizzlyChicken Group Title
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    sorry

    • 2 years ago
  8. nphuongsun93 Group Title
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    still~ same way of solving :P

    • 2 years ago
  9. GrizzlyChicken Group Title
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    damn, theres another error, i'm gonna look it all over again, for some reason copy and pasting changed everything

    • 2 years ago
  10. GrizzlyChicken Group Title
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    at time t is greater or equal to 0. its right now

    • 2 years ago
  11. GrizzlyChicken Group Title
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    so if i put 0 for t, its 2cos(0)

    • 2 years ago
  12. nphuongsun93 Group Title
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    yup, that's the initial position

    • 2 years ago
  13. GrizzlyChicken Group Title
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    is cos(0)=1?

    • 2 years ago
  14. nphuongsun93 Group Title
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    yes

    • 2 years ago
  15. GrizzlyChicken Group Title
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    then for b) derivative of 2 is 0 so its all 0

    • 2 years ago
  16. GrizzlyChicken Group Title
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    maybe

    • 2 years ago
  17. nphuongsun93 Group Title
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    no no, find the derivative of the function x

    • 2 years ago
  18. GrizzlyChicken Group Title
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    so the derivative of 2cos(pi*0)?

    • 2 years ago
  19. GrizzlyChicken Group Title
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    which uses the product rule (0)(cos...)+(2)(-sin(0))

    • 2 years ago
  20. GrizzlyChicken Group Title
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    and sin(0)=0

    • 2 years ago
  21. GrizzlyChicken Group Title
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    so the velocity is 0

    • 2 years ago
  22. nphuongsun93 Group Title
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    wops sorry i'm here x = 2 cos (pi t) x' = -2 pi sin (pi t)

    • 2 years ago
  23. nphuongsun93 Group Title
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    do you know how to derivative?

    • 2 years ago
  24. GrizzlyChicken Group Title
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    yea, did you use the chain rule?

    • 2 years ago
  25. GrizzlyChicken Group Title
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    is that why pi is with -2?

    • 2 years ago
  26. nphuongsun93 Group Title
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    no chain rule. derivative of cos is -sin. pi 's brought out when derivative.

    • 2 years ago
  27. nphuongsun93 Group Title
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    |dw:1349943924669:dw|

    • 2 years ago
  28. nphuongsun93 Group Title
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    derivative again for the acceleration equation

    • 2 years ago
  29. GrizzlyChicken Group Title
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    -2cos(pi*t)

    • 2 years ago
  30. GrizzlyChicken Group Title
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    wait

    • 2 years ago
  31. GrizzlyChicken Group Title
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    -2pi*cos(pi*t)

    • 2 years ago
  32. nphuongsun93 Group Title
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    almost correct, but now pi is brought one more time so it's -2 pi^2 cos (pi t)

    • 2 years ago
  33. GrizzlyChicken Group Title
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    ohhh

    • 2 years ago
  34. nphuongsun93 Group Title
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    x = 2 cos (pi t) x0 = 2 x' = v = -2 pi sin (pi t) v0 = 0 x'' = a = -2 pi^2 cos (pi t) a0 = -2pi^2 and idk how to do d and e

    • 2 years ago
  35. GrizzlyChicken Group Title
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    does the mass move toward the wall because the acceleration is negative?

    • 2 years ago
  36. GrizzlyChicken Group Title
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    oh, thats alright. you've helped me enough.Thanks!

    • 2 years ago
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