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Homework Help: Using kinetic and dynamic principles to determine unknown parameters

  1. Mar 21, 2010 #1
    A motor vehicle has a mass of 700Kg and is travelling at 36 km/h on a level road; it is taken out of gear and allowed to roll to a stop.

    The first part of the question asks me to work out the kinetic energy which I've done and then the next part asks how far will it travel if the rolling resistance between the road and the wheels is 155N? The kinetic coefficient of friction is 0.023.

    I really need help with this, I'm really struggling!

    Thanks in advance!
     
  2. jcsd
  3. Mar 21, 2010 #2
    Start with Newton's laws. Write down the equations of motion that will relate all your parameters
     
  4. Mar 21, 2010 #3
    The Captain is right on the mark Drizzle,

    Keep in mind two things:

    1.) The forces in the vertical direction are equal because the car is not bouncing up or down, [tex]\sum[/tex] F_y = 0

    2.) There is an acceleration in the x-direction, [tex]\sum[/tex] F_x = ma.

    After that you have a simple constant acceleration kinematic situation, find the right formula and solve for the distance.
     
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