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sailsinthesun

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## Homework Statement

Three forces acting on an object are given by F1 = ( 2.20 j ) N, F2 = ( 3.45 j ) N, and F3 = ( - 40.0 i ) N. The object experiences an acceleration of magnitude 3.95 m/s2.

(a) What is the direction of the acceleration?

(b) What is the mass of the object?

(c) If the object is initially at rest, what is its speed after 13.0 s?

(d) What are the velocity components of the object after 13.0 s?

## Homework Equations

f=ma pythagorean theorem

## The Attempt at a Solution

(a)I drew this triangle to find both the resultant force and angle.

http://img255.imageshack.us/img255/2737/trianglejb6.th.jpg

I calculated theta to be 171.9602 deg from positive x-axis using tan theta=(40/5.65)

and calculated R to be 40.3971N.

(b)Taking R from (a), I have f=ma --> m=f/a m=40.3971/3.95=10.2271kg

(c) Using vf=v0t+at we have vf=(0)(13)+(3.95)(13)=51.35m/s

(d)This is the one I'm lost on. I have no idea how to convert to velocity vector.Anyone have any insight on (d)? Also, does the rest of the work look to be correct? Thanks in advance.

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