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Driver and Car

  1. Oct 23, 2007 #1
    1. The problem statement, all variables and given/known data

    A car starts from rest at a stop sign and accelerates to speed 15m/s in a time of 6 seconds. The mass of the car is 300kg and the mass of the rider is 100kg. What is the force on the rider?

    2. Relevant equations

    I figured the acceleration to be 2.5m/s/s. And I know that F = ma.

    3. The attempt at a solution

    I'm not sure if you calculate the force on the car and the driver (400kg), or just the force on the driver (100kg).

    So the equation is either F=(100)(2.5) or F=(400)(2.5). Which one? Do the car and driver act as one mass?
     
    Last edited: Oct 23, 2007
  2. jcsd
  3. Oct 23, 2007 #2

    Dick

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    It asks for "the force on the rider". Not the car.
     
  4. Oct 23, 2007 #3
    I just thought that the driver was in system with the car, so their masses would add up? Is that ever the case?
     
  5. Oct 23, 2007 #4

    Dick

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    If they ask you for the total force you need to push the car AND driver (i.e. how much force does the engine need to provide) then you would add them.
     
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