A runner is being used in the figure shown. The cat lover lifting the 50-pound crate (with cat) is using how much effort (disregard friction, wind resistance, and the weight of the pulley and the rope)?

Hammer faces are commonly made of each of the following materials EXCEPT:

Determine which of the choices best solves the problem shown in the first picture and then mark the corresponding choice on your answer sheet. The problem is presented in the first drawing and the remaining four drawings are possible solutions.

Torsion springs:

Capacitors connected in parallel