Homework Help Forum: College Physics

Posted by Jeff on Sunday, October 25, 2009 at 10:22pm.

The only force acting on a 3.9 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 solved for work by using the changes in kinetic energy and got -75 J but don't see how that helps whatsoever.

• College Physics - Nick M, Sunday, October 25, 2009 at 10:38pm

  F = ma. They gave you Force and mass, solve for acceleration. You can use the values of X they give you, the velocities, and the acceleration to solve for Vf and the X value where v = 5.0

  
  

• College Physics - Jeff, Sunday, October 25, 2009 at 10:42pm

  Yes I know of using that equation but the acceleration is not constant so I can't just plug in into an equation with a different x value.

  
  

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