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suppose you apple a force given by the vector f=(3.5i-2.3j+4.0k) N on an object.

ID: 1295313 • Letter: S

Question

suppose you apple a force given by the vector f=(3.5i-2.3j+4.0k) N
on an object.
a) if the object moves to r=(0.23i+1.0j) m what is the work done?

the work is -1.5 j

b)what is the angle between the two vectors?

the angle is 1.0×10^20

the one I need help is c
c) if the object has a mass of 25.0kg and the force is applied on the object when it is initially moving with a speed of 4.3 m/s. what is the objects final speed ?

(I've been trying to do this problem using w= change in kinetic energy. I got the answer 4.3 m/s which I'm pretty sure is incorrect )
please help

Explanation / Answer

net Work = change in KE

=> - 1.5 = 0.5 m (vf^2 - vi^2)

=> - 1.5 = 12.5 ( vf^2 - 4.3^2)

=> 0.12 = 18.49 - vf^2

so vf = sqrt (18.37)

=> vf = 4.286 m/s