An electric motor has a rating of 4.0 x 10^2 watts. how much time will it take for this motor to lift a 50.-kilogram mass a vertical distance of 8.0 meters?

Which statement is true for light passing into a medium that is more optically dense than the first medium through which it past

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.

If we relied solely on the nonrenewable resources found in the u.s., which one would we run out of first at current usage levels? a. natural gas b. oil c. uranium d. coal