Problem statementSolution video |

**DISCUSSION THREAD**

Any questions?? Ask and answer questions in the discussion thread below.

**DISCUSSION**

**Four-step plan**

**Step 1: FBD**

Draw *individual* free-body diagrams for the two blocks. For this, define a coordinate *y* that describes the motion of the lower block. Let's say you choose *y* to be positive to the left. Be sure that the directions of the spring force on the top block and the dashpot force on the lower block are consistent with your definitions of *x *and *y*.

**Step 2: Kinetics - Newton/Euler**

Write down the Newton equations for the two blocks. Be sure to abide by the sign conventions defined for x and *x *when writing down these equations.

* Step 3: Kinematics*The kinematics that you need here are to relate

*x*and

*y*. For x defined positive to the right and y defined positive to the left, we have

*x*=

*+y*

*.*

**Step 4: Equation of motion**

Combine your equations from Steps 2 and 3 to end up with the differential equation of motion for the system in terms of the coordinate *x*.

Which way is the direction of the force for a dashpot? I am not sure what that is and how it acts in a system.

What is a dashpot and how to I include it in my FBD?

After watching the solution video I'm very confused as to why there was a separate "y" coordinate system for the dashpot. Why are we not able to just use the existing coordinate system for the spring? As using the separate one for the dashpot, and then setting them equal at the end seems redundant.