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geerky42 Group Title

Need help on #11, please. (Momentum)

  • one year ago
  • one year ago

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  1. geerky42 Group Title
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    • one year ago
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  2. geerky42 Group Title
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    I solved #10 and the answer is 109.217 m/s if this help you all.

    • one year ago
  3. geerky42 Group Title
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    I'm not sure exactly what #11 mean; I don't see how this system lost energy during collision.

    • one year ago
  4. wio Group Title
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    By the way, how did you find the velocity?

    • one year ago
  5. geerky42 Group Title
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    Are you telling me that the block lost energy to the spring?

    • one year ago
  6. VeritasVosLiberabit Group Title
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    \[\frac{ 1 }{ 2 }m _{b}v _{b1}^{2}=\frac{ 1 }{ 2 }m _{b}v _{b2}^{2}+\frac{ 1 }{ 2 }kx\] was the formula I got for 10. \[\sqrt{2[\frac{ 1 }{ 2 }(.003kg)(500\frac{ m }{ s })^{2}-\frac{ 1 }{ 2 }(859\frac{ N }{ m })(.02m)]/.003kg}=v _{b2}\]

    • one year ago
  7. VeritasVosLiberabit Group Title
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    my final answer for #10 was 494.24 m/s which makes more sense to me than 109.217 m/s

    • one year ago
  8. VeritasVosLiberabit Group Title
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    but I'm not sure. are you sure your answer for #10 is correct?

    • one year ago
  9. geerky42 Group Title
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    Well, I submitted my answer on online homework and it said it's correct.

    • one year ago
  10. VeritasVosLiberabit Group Title
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    ok, I'm going to retry it then.

    • one year ago
  11. geerky42 Group Title
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    Any idea for #11, @wio ?

    • one year ago
  12. wio Group Title
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    oh sorry I was idle...

    • one year ago
  13. wio Group Title
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    So you figured out how much energy was transferred to the block, and the remaining energy was used to calculate velocity, right?

    • one year ago
  14. wio Group Title
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    Did you try putting the elastic energy as energy lost?

    • one year ago
  15. geerky42 Group Title
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    I did and the answer is incorrect...

    • one year ago
  16. wio Group Title
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    Give me a second...

    • one year ago
  17. wio Group Title
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    What about the conservation of momentum?

    • one year ago
  18. wio Group Title
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    Was momentum give to the block on the spring?

    • one year ago
  19. wio Group Title
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    Figure out the momentum before hand and figure out the momentum later. That would tell you how much momentum the block received. Compare that to the elastic energy.

    • one year ago
  20. wio Group Title
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    I mean, use the momentum of the block to find its velocity and figure out the kinetic energy of the block. Then compare that to the elastic energy.

    • one year ago
  21. wio Group Title
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    That might be what they're asking. It's true that I find it hard to tell. Obviously this is a closed system an no energy is being lost. So maybe what they mean is how much kinetic energy do we expect the block to have, which it won't have.

    • one year ago
  22. wio Group Title
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    If that doesn't work then I'm really stumped here.

    • one year ago
  23. wio Group Title
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    It's a really unfair question in my opinion.

    • one year ago
  24. wio Group Title
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    @geerky42 Have you been looking at the momentum?

    • one year ago
  25. geerky42 Group Title
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    None, It doesn't work... I guess I need to ask my physics teacher a question. Thanks.

    • one year ago
  26. wio Group Title
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    @geerky42 I'm not getting your 109 velocity through energy methods alone

    • one year ago
  27. geerky42 Group Title
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    Sorry I just use conservation of energy to find the speed of block after collision, I then plug the speed of block into conservation of momentum to find the speed of bullet after collision. My brain is dead, sorry about that.

    • one year ago
  28. wio Group Title
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    How did you find the speed of the block then?

    • one year ago
  29. geerky42 Group Title
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    "Sorry I just use conservation of energy to find the speed of block"

    • one year ago
  30. wio Group Title
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    Yeah well the block started with no energy right?

    • one year ago
  31. geerky42 Group Title
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    Right.

    • one year ago
  32. wio Group Title
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    It got elastic energy

    • one year ago
  33. wio Group Title
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    you converted that into kinetic energy?

    • one year ago
  34. geerky42 Group Title
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    Well, it moves so it should have kinetic energy.

    • one year ago
  35. wio Group Title
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    How did you find out how much bullet energy went into kinetic energy then?

    • one year ago
  36. geerky42 Group Title
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    I don't find it from bullet, I did work "backward." We know that the spring has been compressed by 2 cm and from that we can find elastic energy and then from that, we can convert it into kinetic energy. That's how I find the speed of block.

    • one year ago
  37. geerky42 Group Title
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    Kinetic energy instantly after collision.

    • one year ago
  38. geerky42 Group Title
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    I don't see how system lost the energy, spring absorb energy from block that has been hit by bullet.

    • one year ago
  39. geerky42 Group Title
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    The surface is frictionless. I don't know what else cause it to lost energy...

    • one year ago
  40. wio Group Title
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    Oh, did you try entering the change in kinetic energy of the bullet?

    • one year ago
  41. geerky42 Group Title
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    No, how can this help me?

    • one year ago
  42. wio Group Title
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    Because it would be the amount of energy the bullet lost

    • one year ago
  43. geerky42 Group Title
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    None, still don't work...

    • one year ago
  44. wio Group Title
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    What are you getting for it though?

    • one year ago
  45. geerky42 Group Title
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    17.143 J

    • one year ago
  46. wio Group Title
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    No, that's the new KE of the bullet. I said the change.

    • one year ago
  47. wio Group Title
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    Meaning the first KE minus the new KE

    • one year ago
  48. geerky42 Group Title
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    I did this, I got this answer.

    • one year ago
  49. wio Group Title
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    your original KE wasn't 375?

    • one year ago
  50. wio Group Title
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    and new KE isn't 17?

    • one year ago
  51. geerky42 Group Title
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    Forgot to square one of the velocity, I got 357.107 J

    • one year ago
  52. wio Group Title
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    Yes, that's what I'm getting as the change in bullet eneryg.

    • one year ago
  53. geerky42 Group Title
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    Submitted this answer; it's still wrong...

    • one year ago
  54. geerky42 Group Title
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    I guess I have to see my teacher and talk about it.

    • one year ago
  55. wio Group Title
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    yeah sorry

    • one year ago
  56. geerky42 Group Title
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    Thanks for your time and patience, though.

    • one year ago
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