Please Help Me with Physics!?

Question

I would appreciate any helpful input on this physics problem. I am really confused on this one. Thanks for any help :)

The force of magnitude Fx acting on a 2.00 kg particle varies in time as shown in the figure below:

http://www.webassign.net/sercp/p6-12.gif

a) Find the impulse of the force.
b) Find the final velocity of the particle if it is initially at rest.
c) Find the final velocity of the particle if it is initially moving along the x axis with a velocity of -2.00 m/s.

Answer 1

Hello
I'm sorry that I may not write good in english because I am Iranian.
answer a> did you mean acceleration by impulse? If yes: according to the third rule of newton it is a=f/m a is acceleration f is force and m is mass so your acceleration is changing along the time.
in every point of time u can calculate it.
b> maximum velocity will be 6 when you draw the acceleration along time length the area under that line is your changes in veloity.
c>as I said in b the change in velocity wil be 6 and because the first speed was -2 the final velocity will be -2+6=4 4 is answer

Answer 2

The impulse is I = ∫f*dt. You have the plot of f vs t, the integral is just the area under the plot. You can use geometry to get that.

The total impulse equals change in momentum. In your problem, intial momentum = 0, so the change is just the final momentum, or m*vf = I

In the last part, you have an initial momentum, which is negative. The change in momentum will then be the initial PLUS the final momentum, Again, this equals the impulse I