What is the value of F_max for an impulse of 6.8 Ns in the given figure?

[krej]

Homework Statement

In the figure , what value of F_max gives an impulse of 6.8 Ns?
http://img76.imageshack.us/img76/1782/09ex05.jpg

Homework Equations

Integral of F with respect to time equals impulse

The Attempt at a Solution

I tried doing two things, and they were both wrong.

First, i tried the integral of F with respect to time from 0 to 8 = 6.8.
Ft from 0 to 8 = 6.8
F(8) - F(0) = 6.8
F = 6.8/8
F = 0.85
I realize that is wrong though, since the picture they give us isn't of constant force.

So then I tried using the area of a triangle:
Area = (1/2)b*h
Area = (1/2)*8*h
4h = 6.8
h = 6.8/4 = 1.7

So I entered 1.7 into the website, and it said it was wrong. If that didn't work, I have no idea what else I could do to find it.

 

[faradayslaw]

Homework Statement

In the figure , what value of F_max gives an impulse of 6.8 Ns?
http://img76.imageshack.us/img76/1782/09ex05.jpg

Homework Equations

Integral of F with respect to time equals impulse

The Attempt at a Solution

I tried doing two things, and they were both wrong.

First, i tried the integral of F with respect to time from 0 to 8 = 6.8.
Ft from 0 to 8 = 6.8
F(8) - F(0) = 6.8
F = 6.8/8
F = 0.85
I realize that is wrong though, since the picture they give us isn't of constant force.

So then I tried using the area of a triangle:
Area = (1/2)b*h
Area = (1/2)*8*h
4h = 6.8
h = 6.8/4 = 1.7

So I entered 1.7 into the website, and it said it was wrong. If that didn't work, I have no idea what else I could do to find it.

Note that the units on the time axis are miliseconds. Hence, 4x10^-3*Fmax==6.8, Fmax==1700N.

 

[krej]

Oh, wow I didn't notice that at all. I'm too used to it always being in seconds I didn't even think about looking at that. :p

Thanks a lot for your help!