# Homework H4.J - Fa22

Discussion and hints:

The constant applied force F acts only in the x-direction. Therefore, as explained in the lecture book, the work done by F is simply the force multiplied by the distance traveled by particle A in the x-direction. Use this result 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 system made up of A+B+bar. 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 system. The KE for the system is the sum of that for A and B. The PE for the system is the sum of that for A and B. Consider the above discussion when calculating the work done by the force F.

Step 3: Kinematics
What is the horizontal distance traveled by B? How are the speeds of A and B related to the angular speed of the bar?

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

Any questions??

## 3 thoughts on “Homework H4.J - Fa22”

1. Katherine says:

The only work in this problem is done by F, correct?

1. Drew Payne says:

Right, all other work done on the system (gravity) is conservative, so you account for it with the change in potential energy

2. George West Wehmann says:

Do we consider the distance F moves point B or just point A?