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Homework Help: Analyzing Force vs. Time graphs

  1. Oct 30, 2007 #1
    1. I REALLY need help here! I've been doing pretty good in physics so far this year, but a new quiz devastated me. Here's the problem:
    I was given a Force vs. Time graph and a lot of the questions pertained to the mass of the object. How do I find the mass only given a F vs T graph?

    2. Relevant equations
    Is there any other data I can obtain from a Force/Time graph? (like acceleration, velocity, or something to do w/ friction)?
  2. jcsd
  3. Oct 30, 2007 #2


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    A force time graph is all about impulse, and impulse is the change in momentum of an object.
  4. Oct 30, 2007 #3
    Impulse is given by the area under an F-t graph.

    As Kurdt said, impulse is the change in momentum of an object. ie. p2 - p1 or m(v2 - v1) [for constant mass].
  5. Oct 31, 2007 #4
    If you're solely given the Force of an object over Time... I don't see how you could find the mass of the object unless you were somehow able to calculate the acceleration.

    If the object was traveling around a circular path, and you were given the velocity or able to calculate the velocity and the radius of the circle, then you could substitute (v^2)/r as the acceleration...

    But I believe, as in introductory physics, the equation F=ma has to come into play here.
    (or F=(mv^2)/r)

    NOW, you might have been told that this was a free-falling object, or a nuance similar. In which case, that gives you the acceleration (9.8 m/s^2)- so it may be tricky.
  6. Oct 31, 2007 #5
    If it is analysing a collision, which F-t graphs are so often used for, and you know the initial and final velocities, then the mass can be found from the relationship in my last post.
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