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Physics 161, Forces

  1. Sep 21, 2011 #1
    1. The problem statement, all variables and given/known data

    1. A 340 kg rocket sled can be accelerated at a constant rate from rest to 1900 km/h in 2.6 s. What is the magnitude of the required net force?

    2. Relevant equations

    3. The attempt at a solution
    1. So I tried calculating the acceleration and multiplying it by the mass. For the acceleration I tried dividing 1900km/h by 2.6s and multiplying it by the mass however that did not work.
  2. jcsd
  3. Sep 21, 2011 #2


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    This may sound silly, but you did convert the 1900 km/h to m/s didn't you?
  4. Sep 21, 2011 #3
    Yes sorry I did do that, forgot to mention that above
  5. Sep 22, 2011 #4


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    Ok approximating

    1900km/h is a little over 500 m/s

    A little over 500 in 2.6 must be about 500 in 2.5 seconds so acceleration is around 200 ms-2

    F = ma says 200 * 340 so approx 68 000 N

    What answer did you get?
  6. Sep 22, 2011 #5
    Sweet thanks! I just forgot about the squared part on 200m/s
  7. Sep 22, 2011 #6


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    Are you saying the only error you had was in the units of an answer??? because none of the numbers in this problem are squared?????
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