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Exam Questions- Need Help Please

  1. Jan 28, 2007 #1
    1. The problem statement, all variables and given/known data
    a 47kg women balances on one heel of a high heeled show. if the heel has a radius of 1.4cm what pressure does she exert on the floor?










    2. Relevant equations
    rho=m
    v


    3. The attempt at a solution
    = 47kg = 33.5
    1.4cm





    1. The problem statement, all variables and given/known data
    The pascal principle is used to operate a dentists chair. assume that the pressure everywhere in the fluid is 13.5 kpa. if the small cylinder(piston) has an area of 0.007m(squared) and the large cylinder(piston) has an area of 0.08m(squared) calculate the force on each cylinder.










    2. Relevant equations
    i think the equation is f=af
    a


    3. The attempt at a solution
    =(3.14)(0.007)squared(13.5)
    0.08(squared)
    =.32





    1. The problem statement, all variables and given/known data
    a gold nugget weighs 1.23N in air. when suspended from a string and submerged in water its apparent weight (T) is 1.09N. calculate the density of the gold nuggett.










    2. Relevant equations
    density=mass
    volume


    3. The attempt at a solution
    = 1.23N
    (3.14)r(squared) x h
    =





    1. The problem statement, all variables and given/known data
    water enters a cylindrical pipe 3.5cm in diameter at a speed of 1.6m/s. if the pipes diameter is suddenly reduced to 2.1cm, what is the max velocity of the water moving through the smaller pipe?










    2. Relevant equations
    AV=AV


    3. The attempt at a solution
    3.14(3.5)(1.6)=A(2.1)





    1. The problem statement, all variables and given/known data
    air is pushed through a forced-air furnace duct at a speed of 4.7m/s. the duct is rectangular and measure 58cm by 23cm. how fast will air move through a smaller portion of the duct that is also rectangular and measures 35cm by 23cm.










    2. Relevant equations
    AV=AV


    3. The attempt at a solution
    3.14(58)V=23(4.7)





    1. The problem statement, all variables and given/known data
    a force of 19N[E] pushes a box of mass 13.2kg across a level floor at a constant speed. calculate the coefficient of kinetic friction (,U) between the two surfaces.










    2. Relevant equations
    ,U=f
    mg


    3. The attempt at a solution

    = 19
    13.2(9.80)
    = 19
    129
    =0.14
    129








    i know its a lot of work there so you can do all of them or just 1 or how every many you want to. im just struggling on these questions and my exam is tomorrow and i really need some help so if you guys are able to help me out i would really appreciate it. thanks so much for doing this guys. :smile:
    oh and u can delete my other thread since i read cristos post.
     
  2. jcsd
  3. Jan 28, 2007 #2
    In response to your first question:

    Pressure is defined as a force per unit area. You are given mass and, assuming the woman is on Earth, the force exerted by her shoe can easily be found by basic mechanics.
     
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