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PCAT Problem please Help

  1. Mar 4, 2007 #1
    A person pushes a 14kg lawn mover at constant sped with a force of 88N directed along the handle, which is at an angle of 45 degress to the horizontal. (a) draw the Free-body diagram showing all forces acting on the mower. (b) Calculate the horizontal friction force on the mower, then (c) the normal force exerted vertically upward on the mower by the ground. (d) What force must the person exert on the lawn mower accelerate it from rest to 1.5m/s in 2.5 seconds, assuming the same friction force?

    This is a problem on my practice PCAT test for Pharmacy school. And its been a while since I have had physics so any help would be appreciated.

    Thanks
     
  2. jcsd
  3. Mar 4, 2007 #2
    well here are some eqns to consider,

    F=ma therefore if an object isn't accelerating the net forces are zero.
    The "normal" force is the one from the earth pushing upwards on the mower; from the above comment, if the mower isn't burrowing underground, the Normal force must then equal the weight of the mower plus whatever part of the push is directed vertically.

    Vf=Vi+at (linear acceleration, relating time, initial and final velocities)

    PS: I sympathize, I am myself brushing the rust off of 20 years of non-use since school. Sort of like riding a bike, but more like riding one with a blindfold, as I have had to reaquaint myself with all the tricks that were once second nature. Can be done, just in the future try to figure out what eqns might be relevant and some reasoning as to which ones might be most useful. You'll get a lot more help that way.
     
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