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Newton's laws. Force and Tension help

  1. Feb 8, 2010 #1
    1. The problem statement, all variables and given/known data
    A 1420 kg jet engine is fastened to the fuselage of a passenger jet by just three bolts (this is the usual practice). Assume that each bolt supports one-third of the load.

    (a) Calculate the force on each bolt as the plane waits on line for clearance to take off.

    (b) During flight, the plane encounters turbulence, which suddenly imparts an upward vertical acceleration of 2.1 m/s2 to the plane. Calculate the force on each bolt now.


    My second question is this...
    2. A force F of magnitude 10 N is applied to a FedEx box of mass m2 = 1.0 kg. The force is directed up a plane tilted by θ = 37°. The box is connected by a cord to a UPS box of mass 2.5 kg on the floor. The floor, plane, and pulley are frictionless, and the masses of the pulley and cord are negligible. What is the tension in the cord?

    hrw7_5-66.gif

    2. Relevant equations

    Fnet = m * a

    I think these equations work, not sure though.
    F-T-m2*g*sin37= m2 * a1
    T= m1 * a2
    (F-T- m2 * g * sin37)/m2= T/m1

    3. The attempt at a solution

    1. (a). I got this one correct, it is 4638.7 N.

    (b). This one I thought I did correct but it keeps telling me I am doing it wrong. I did (1420 * 9.80) - (1420 * 2.1) = 10934. Then I devided 10934 by 3 and got 3644.7 but it keeps saying that is wrong.

    As for the second question, I wasn't sure how to work those problems as those equations require the acceleration, and I wasn't sure how to get that.

    I tried to do 2.5*cos37, but then I though that you couldn't do that with the weight. I am really stuck on this one.
     

    Attached Files:

    Last edited: Feb 8, 2010
  2. jcsd
  3. Feb 9, 2010 #2
    for question 1 part b:

    there is an upward vertical acceleration =2.1 m/s*s .. What you have done is assuming that this acceleration is divided into 3 parts, try applying this acceleration (2.1) to each part , what answer you will end up??


    As for question 2, I suggest you start by drawing free body diagrams for m1 and m2 , and see what forces act on each of them by applying newtons 2nd law ..
     
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