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Forces Problem (find acceleration of bottle and how far it travels from rest.)

  1. Jan 17, 2010 #1
    1. The problem statement, all variables and given/known data
    David pushes on a .50 kg bottle of water with a force of 3.5 N (R). The coefficient of friction between the bottle and the desk is .20. Using the dynamics worksheet format below, find the acceleration of the bottle and how far it travels in 3.0 s if it starts from rest.


    2. Relevant equations
    Not sure which ones to use:
    -> Fnet=Fa-Ff
    -> Fa = 3.5 N (E)
    -> Ff= coefficient of friction*Fg
    -> Fg= mg

    Forces acting on bottle: Fg, Fn, Ff, Fa

    3. The attempt at a solution

    Fa=3.5N
    coefficient of friction=.20
    a=?
    t=3.0s
    V2=?
    V1= 0m/s^2
     
  2. jcsd
  3. Jan 17, 2010 #2

    PhanthomJay

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    Don't forget Newton's 2nd law in your relevant equations (F_net =ma). Then you can solve for the acceleration. Also, how about then using the kinematic equation of motion that relates distance with time and acceleration?
     
  4. Jan 17, 2010 #3
    Using Ff = uFN, find force of friction. So Ff = (0.20)(0.50)(9.8) = 0.98 N
    Find the net force by subtracting 0.98 N from 3.5 N = 2.52 N.
    Then using F=ma, find a. 2.52/0.50 = 5.04 m/s^2

    Using d= vit + 0.5 at^2, you can find d.

    so d = (0)(3) + (0.5)(5.04)(3^2) = 22.68 m.

    This this right
     
  5. Jan 17, 2010 #4

    PhanthomJay

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    :approve:Looks real good!
     
  6. Jan 17, 2010 #5
    Thank you very much
     
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