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Homework Help: Cars and Case Studies

  1. Mar 25, 2008 #1
    For each part of this question, consider a vehicle that is travelling at a speed of 30m/s and then stops as described.
    a) The vehicle stops under normal braking conditions over 100 metres.
    b) The vehicle stops due to a collision when there are ineffective crumple zones (e.g. the vehicle is a 4WD with a rigid chassis and bulbar). Collision time = 0.2 seconds.
    c) The vehicles stop due to a front-on collision when there are effectgive crumple zones on the vehicle. Collision time = 0.8 seconds.

    For each of the situations above:
    i) Describe the changes to energy and momentum that occur as the car stops.
    ii) Calculate the force required to stop an 80kg person in the car.
    iii) Calculate the distance and time taken to stop.
    iv) Discuss the differences between the magnitudes of kinetic energy, momentum, force, distance and time in the three different situations.
  2. jcsd
  3. Mar 25, 2008 #2
    As i have already been told a lot not to give direct answers..you must be content with hints.:

    1)change in k.e. and (mv2-mv1)
    2)Force= mass * acceleration
    3)Collision changes its velocity.
  4. Mar 25, 2008 #3
    I'm not very clear on your hints I'm afraid mate.
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