Question

http://session.masteringphysics.com/problemAsset/1167406/2/jfk.Figure.05.U51EOC.jpg

The figure below shows the force acting on a 2.0 kg object as it moves along the x-axis. The object is at rest at the origin at t=0 s. What are its acceleration and velocity at t=6 I put the link of the picture above

Answer 1

Since Force is Mass times Acceleration, you know that if you have a force, you have an acceleration. So what's happening at t=6? It looks like the force is 0. No force means no acceleration. However, acceleration is a change in velocity. After an object gets in motion it tends to stay in motion. So all the previous accelerations it experienced have affected the velocity, which is now constant. It looks like it accelerated for 3 seconds at 4 newtons and then accelerated for another 2 seconds in the opposite direction at 2 newtons, or we can call it -2 newtons, since the negative gives it a direction, that's why it's a vector.

Now you know the force and the mass, so you can solve for your accelerations during that time. F/m=a

Use your regular kinematic equation Vfinal=Vinitial*at to find out your velocity. Remember that since it undergoes two different accelerations that you have to use this equation twice and use the final velocity from the first acceleration as the initial velocity when calculating the final velocity due to the second acceleration since it will still be in motion!

Anything you still need help with I'd be glad to help!