Recent content by pevi70

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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    What does that mean? And do you agree with JBA?
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    Thanks Nidum, what is it? Do you agree with JBA?
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    OK, I thought it didnt apply. Thats great, thanks a million!
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    I think s=1/2vt only applies if the acceleration is constant.
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    Here is a picture of the bow: (The width of the wooden part of the bow is 4 cm)
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    These bows are so strong, you need a special lever to charge the spring.
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    Thats simply not practical. You need a special lever to lock the spring. I can measure the speed of the arrow. I would really appreciate it if someone could help me how to calculate the time needed to propel the arrow by the spring in an idealized environment.
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    Despite the picture, quite some assumptions need to made: no recoil for example. If you would assume that the propulsion is coming only from a mass less rubber spring, no friction exists, how would you calculate the time it would take for the arrow to cross the 17.5 cm (knowing the final speed)...
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    The rubberband has a round shape (rod shape) with a diameter of about 5 mm. I will post a picture of the actual bow later today. I have no equipment to measure extensions under different loads, so I don't have or can easily collect that information.
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    This is the set-up: I can measure the velocity of the departing arrow. The mass of the rubberband spring is unknown and not practical to measure. I would be interested to use the velocity and the other known parameters to calculate bow characteristics including the power of the bow. Let me...
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    It is indeed a rubberband connected to a 1 square cm metal bar.
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    That would be the following graph So 17,5 * 0.9389 / 2 ?
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    @ Dr D, I was trying to show how I could correct for the fact that the path of the arrow is not the same as the extension of the spring. I calculated for each cm along the path of the arrow, the length of the spring and from that the extension of the spring. As you can see there is a polynomial...
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    Crossbow Physics: Calculating Spring Constant, Tension Force & Power

    I would appreciate it if you could help with the differential. I have no clue as what do next to be able to calculate the time. Thanks!
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