A crane is used to suspend an I-beam in place while welders attach it to the support beams. If the beam weighs 400 N and is held in place for 80 seconds, how much power did the crane exert on the
I-beam?
none. It didn't do any work
5W
32000 W
9.8 N

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.