# Vector components problem determinings final kinetic energy

1. Nov 21, 2009

### synergix

1. The problem statement, all variables and given/known data

question 2

http://web.viu.ca/hearnd/Courses/Phys121/F02Test2/Page%201.htm" [Broken]
3. The attempt at a solution

I have been trying to do question 2 on the practice test but I am stuck.
I was trying to calculate the final velocities along each vector by using the equation
vxf^2=vxi^2+2aX
first i determined the acceleration by dividing each of the force vectors by the mass of the object
but since one of the accelerations was negative I could not calculate the final velocity of that vector

so now I am trying with the total vectors for

sqrt(4^2 +0 +0)

because only one component out of three has any initial velocity

so vi=4m/s

F=sqrt(4^2+(-3)^2+2^2)=5.385N
so
a= 2.69258 m/s

d=sqrt(16^2+4^2+8^2)= 18.3303

v=sqrt(4+2(2.69258)(18.3303))
vf=10.13

Ek=106.09

which is wrong

any help would be appreciated

Last edited by a moderator: May 4, 2017
2. Nov 21, 2009

### rl.bhat

Work done = F.r = Change in KE.

3. Nov 21, 2009

Thanks