- #1

jdawg

- 367

- 2

**Finding F1 -- Summing forces on a box**

## Homework Statement

There are two forces on the 2.80 kg box in the overhead view of the figure but only one is shown. For F1 = 10.9 N, a = 10.2 m/s2, and θ = 34.9°, find the second force (a) in unit-vector notation and as (b) a magnitude and (c) a direction. (State the direction as a negative angle measured from the +x direction.)

I'm not sure if this link will work, but here's the picture: http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/c05/fig05_32.gif

## Homework Equations

∑F=ma

∑F=F

_{1}+F

_{2}...+

## The Attempt at a Solution

Ok so I've been stuck on this one for a while. I started out finding the sum of the forces:

∑F=(2.8kg)(10.2m/s

^{2})=28.56 N

Then I tried solving for F

_{2}:

28.56N=10.9N+F

_{2}

F

_{2}=17.66

Then I found the x and y components of the acceleration:

a

_{x}=10.2*sin(34.9)=5.84m/s

^{2}

a

_{y}=10.2*cos(34.9)=8.37m/s

^{2}

Could you multiply a

_{x}and a

_{y}by the mass and get the F

_{1x}and F

_{1y}?

I'm so confused, could someone please help guide me through this problem?