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Homework Help: How do I find an unknown weight ?

  1. Mar 14, 2005 #1
    Here is the problem that was set up as a lab experiment.
    We ran a car on a Rail (assumed to be frictionless) and collided it with another (stationary) car. There were three trials and I have gathered thwe average of the the
    Next we added three rayovac cells to the car and repeated the same process.

    I will provide the work already performed (i do not think it is correct) but here goes.

    the weight of the car without batteries is 985.5g = 0.986kg

    the impacted car car is posistioned at 100cm on the rail. Xi =100cm = 1m
    average Xf = 38 cm = .37m

    Ti =0, average Tf =4.25s

    We are to find the following:

    Here goes The problem states to find the following
    1. Acceleration 5. Work
    2. mass 6.the weight of three rayovac cells placed on the object
    3. Force 7. momentum with and without cells
    4. KE 8. Impulse upon collision

    This is the work I have completed so far.
    a = (Vf - Vi/t), Vi = 0, Vf = d/t = -0.63m/4.25s = -0.15m/s
    a = (-0.15m/s)/4.25s =-0.035m/s^2
    m = w/g = (0.986kg) / (9.8m/s^2) = 0.1N
    F = m x a = (0.1N) (-0.035m/s^2) = -3.5 x 10^-3 (N)(m/s^2)
    KE = (1/2)mv^2 = (1/2) (0.1N) (-0.15m/s)^2 = 11.25 x10^-4 J

    W = (FcosO)X = (3.5 x 10^-3) (-.62m) = -2.17 x10^-4 J

    I do not know how to calculate the weight of the car with the cells.
    The process is the same with 3 runs the average time and distance are

    Xi = 100cm = 1m, Xf = 51.67cm, = .52m
    Ti = 0 Tf = 3.25s

    I have no idea how to do the rest of this exercise. :surprised I am willing to do the work :grumpy: but I need some direction o:) . Any help at all will be greatly appreciated. I need to know how to do this work for a test in my next class meeting. :cry:

  2. jcsd
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