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How much force and energy for moving a frictionless object

  1. Jan 31, 2016 #1
    1. The problem statement, all variables and given/known data
    I have an object of 10 kg
    It is to be displaced 2 meters
    Assume a frictionless surface, and no wind resistance
    The object begins as stationary, then is moved that distance in the span of .5 seconds.

    2. Relevant equations
    Force = mass* acceleration
    acceleration = (delta velocity) / time
    velocity = (delta position) / time

    3. The attempt at a solution
    initial velocity is 0
    final velocity is: (2 - 0) meters / .5 second = 2 meters / .5 seconds= 4 meters per second
    acceleration = (4 m/s - 0 m/s) / .5 seconds = 8 meters / second^2
    8(m/s^2) * 10 kg = 80 Newtons

    Correct?
     
  2. jcsd
  3. Jan 31, 2016 #2

    haruspex

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    You have mot stated what you are asked to find. You seem to have assumed a constant force. Is that given?
     
  4. Jan 31, 2016 #3

    berkeman

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    Are you told to assume a constant force?
     
  5. Jan 31, 2016 #4

    haruspex

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    You have not provided the whole question. What exactly are you supposed to find? Minimum energy? Least maximum magnitude force?
    As berkeman posted, you seem to have assumed a constant force, but even then your calculation is wrong:
    That calculates the average speed, not the final speed. Check your answer: constant acceleration of 8m/s2 for 0.5 seconds from rest would travel how far?
     
  6. Jan 31, 2016 #5
    What do you all mean when you say: "constant force"?

    What would this constant force do? What are its attributes?

    .5^2 = .25
    .25 *8 = 2
    since the object moved 2 meters, this appears correct. Or what am I missing?
     
  7. Jan 31, 2016 #6

    haruspex

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    Review the equation relating time, distance, initial speed, and constant acceleration. You are missing something.

    Please state the entire question, exactly as presented to you.
     
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