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Homework Help: Urgent Physics help needed 4 a damsel in distress!

  1. Sep 9, 2004 #1
    Please help me with this question!!! I understand the concepts of potential difference and charge etc but i dont understand what to do with the velocity.
    1) In a lightning flash, the potential difference between the cloud and the ground is 1.0 x 10exp9 V and the quantity of charge transferred is 30 C. What is the change in potential energy of the transferred charge? if all of that energy could be used to accelerate a 1000 kg car from rest, what would be the car's final speed?

    Thank you so much for your help!!!
  2. jcsd
  3. Sep 9, 2004 #2


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    The change in potential energy will be equal and opposite the change in kinetic energy of the charged particles (electrons). (Actually some of that goes into heating the air on the way down but I think you're expected to ignore that).

    Just multiply the charge by the (initial) potential difference to find the energy.
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