When you pull on the pulley with a force of 120 n, the pulley applies a force of 800 n to the boxes. what is the mechanical advantage of the pulley?

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.

Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made.