Example 5: A toilet seat-cover

When turning the seat cover of a toilet down, one has to hold the cover and move it down to the toilet seat. Otherwise, the cover would impact on the seat and generate a loud sound. How could this be avoided?

It is demonstrated in a video clip in Model 3 of this chapter that an over-critically damped steel strip returns to its original position slowly and smoothly without experiencing vibration. This concept has been developed and used to design the seat-covers of some modern toilets. The video below shows how the cover moves slowly and gradually to the toilet seat without holding it.