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Cannonball conceptual question

  1. Apr 8, 2013 #1
    1. Problem statement
    Immediately after being fired from a cannon, a high speed cannonball does not posses..

    a) mass
    b) force
    c) momentum
    d) kinetic energy
    e) but, it has all these qualities while moving!

    2. Related equations

    3. Attempt at solution
    I'm thinking the cannon ball does not possess momentum since there are external forces acting upon the object and if we are just looking at the ball by itself, it is not part of a 2-part system which is needed to have momentum.

    Or if that's wrong I think it must have all the qualities because the ball has mass, force came from the cannon thus giving it momentum and it also possesses kinetic energy since the object is moving
     
  2. jcsd
  3. Apr 8, 2013 #2
    What IS momentum?

    And what force acts on the canonball after it has left the barrel?
     
  4. Apr 8, 2013 #3
    Momentum occurs when a 2-part system's internal forces act upon each other or collide

    And the external forces that are acting on the ball after it leaves the cannon would be gravity
     
  5. Apr 8, 2013 #4

    arildno

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    Really?
    What does your textbook define momentum to be?
     
  6. Apr 8, 2013 #5
    momentum is by Google definition, the quantity of motion of a moving body , measured as a product of its mass and velocity

    So does that mean anything that is moving has momentum? Isn't it possible to not have momentum but have kinetic energy?
     
  7. Apr 8, 2013 #6

    arildno

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    "So does that mean anything that is moving has momentum"
    Yes.
    "Isn't it possible to not have momentum but have kinetic energy?"
    No.
     
  8. Apr 8, 2013 #7
    What about the air? Does it act on the ball in any way?
     
  9. Apr 8, 2013 #8
    Air resistance would be a force acting the opposite direction of the cannonball and would cause it to slow down
     
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