Discussion and hints:

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

Step 1: FBDs
Draw a single free body diagram for the system made up of links OA and AB, along with slider B, combined.

Step 2: Kinetics (work/energy)

• Write down the kinetic expressions for the two links and the slider, individually, and then add those together to find the total KE for the system of your FBD. For each KE expression, recall that your reference point for the rotational component needs to be either the center of mass of the body, or a fixed point on the rigid body.
• Do the same for the potential energies, if needed: write down the PEs for each body individually and add together. Also, include the PE of the spring.
• Also, based on your FBD above, which, if any force or couple, does nonconservative work on the system in your FBD? Determine work for such a force/couple.

Step 3: Kinematics
Where is the instant center (IC) for link AB for position 2? (Please refer back to Chapter 2 of the lecture book if you need to review locating ICs.) What does the location of this IC say about the angular speed of link AB? And, what does it say about the speeds of points A and B? Does the freeze frame image of the mechanism shown below agree with your analysis?

Step 4: Solve
Solve your equations above for the speed of slider B.

Any questions?