What do you call the rectangular blocks that are stacked and fastened to the cables and the elevator car?

The correctly identified term for the rectangular blocks that are stacked and fastened to the cables and the elevator car is "Counterweights." In elevator systems, counterweights play an essential role in balancing the weight of the elevator car itself. This balance reduces the amount of energy required to lift and lower the car, making the system more efficient.

Counterweights are typically designed to counterbalance the weight of the car, helping to maintain stability and smooth operation. They are connected to the elevator cables and work in conjunction with the elevator's hoisting mechanism to ensure that the car moves up and down efficiently. This assists in reducing wear on the motor and minimizes energy consumption, which is critical for the overall performance of the elevator system.

Understanding the function of counterweights is fundamental for anyone studying building utilities or elevator systems, as it directly impacts safety, functionality, and energy use in vertical transportation.