Discussion and hints:

The constant applied force F acts only in the negative x-direction (where x is defined as being positive to the right). Therefore, as explained in the lecture book, the work done by F is simply the force multiplied by the distance traveled by the block in the negative x-direction. From the above animation of the simulation results, when the block is on the left side of the track, the work done is positive, and when the block is on the right side of the track, the work is negative. The work done by F is to be found in the Step 2 of your analysis.

Recall the following four-step plan outline in the lecture book and discussed in lecture:

Step 1: FBD
Draw a free body diagram of the block. Which, if any, forces do non-conservative work on this system? Can you justify this from the FBD?

Step 2: Kinetics (work/energy equation)
Write down the work energy equation for the block. Consider the above discussion when calculating the work done by the force F.

Step 3: Kinematics
What is the horizontal distance traveled by the block?

Step 4: Solve
Solve your work/energy equation for the speed of the block.

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Any questions??