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# Physics/Momentum and impulse

Question
I really have no idea what to do for this problem. Any help would be greatly appreciated.

What impulse does the force shown in the figure exert on a 250 g particle?

The graph/figure starts at (0, 1000). It is a constant line until (2, 1000) and then starts decreasing until the point (6,0). This is the point that touches the x-axis at (6,0) and the graph ends at this point. The y-axis is in terms of F_x (N) and the x-axis is in terms of miliseconds (ms).

Hello Nick,

Impulse is force*the time period of the force. When the force is changing in a complex way and you have an equation giving the relationship between force and time, you might need to integrate. Impulse is the area under a plot of force vs. time. In this case, you can break the area under this curve into 2 sections whose area is easy to calculate. I'll assume the units of the force is Newtons, so the max force is 1000 N. And I assume the time is in seconds.

The portion from 0,0 to 2,1000 is a rectangle, so the area is 2000 N.s.

The remaining portion is a triangle. The base is 4 s wide and 1000 N tall. The area is
(1/2)*1000 N*4 s = 2000 N.s

So the total impulse is 4000 N.s. Notice that calculating the impulse does not involve the mass of the particle.

I hope this helps,
Steve
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Physics

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#### Steve Johnson

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I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.

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I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

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BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University