How Does Force Affect Velocity in a One-Dimensional System?

[brittkub1291]

The only force acting on a 1.8 kg body as it moves along the positive x-axis has an x component Fx = - 6x N, where x is in meters. The velocity of the body at x = 3.0 m is 8.0 m/s.



(a) What is the velocity of the body at x = 4.0 m?

(b) At what positive value of x will the body have a velocity of 5.0 m/s?



I think to start off i need to take the integral of Fx=-6xN, which would be -3x^2. But from there I'm a bit confused. It doesn't give the force acting on it, so i don't know how to find the work since W=F*Fx.

 

[nasu]

The only force acting on a 1.8 kg body as it moves along the positive x-axis has an x component Fx = - 6x N, where x is in meters. The velocity of the body at x = 3.0 m is 8.0 m/s.
(a) What is the velocity of the body at x = 4.0 m?

(b) At what positive value of x will the body have a velocity of 5.0 m/s?
I think to start off i need to take the integral of Fx=-6xN, which would be -3x^2. But from there I'm a bit confused. It doesn't give the force acting on it, so i don't know how to find the work since W=F*Fx.

The integral you did IS the work.
You did integral of Fx*dx and this is dW . The integral is the total work.

And no, the work is not W=F*Fx.
Fx is the force