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Force v. Time Graphs

  • Thread starter kk727
  • Start date
  • #1
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Homework Statement


I was given this worksheet today:
http://www.mrwaynesclass.com/impulse/WS/momentum.pdf

However, I was not in school today nor when we started momentum. So I'm a little confused with the graphs. On a force versus time graph, how do you go about solving for velocity? An example problem would be #37. They give you the answer to be -1 m/s (answers are at the bottom) but how do you get there?


Homework Equations


P=mv
ΔP/ΔT = F
F=ma


The Attempt at a Solution



I figured that impulse (ΔP) would be area under the curve, so I calculated that. But using the force and time on the graph, the impulse didn't match up and I just got all confused and frustrated. Can anyone help?
 

Answers and Replies

  • #2
54
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I just realized that the worksheet has two problems that are #37... -_- So I'm doubting that -1 m/s is the answer to this one. I'm still confused with trying to solve it, though!
 
  • #3
559
8
I just realized that the worksheet has two problems that are #37... -_- So I'm doubting that -1 m/s is the answer to this one. I'm still confused with trying to solve it, though!
There is no way it's -1...
Try doing this:
Using F=ma, you can get the acceleration, right? With the acceleration you can use the kinematics equations to get the answer.

You have:
Vi = 0
Acceleration = You find it
Time = 20 s
Vf = ? (solve)

So you can use:
vf = vi + at
 

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