3)110 Watts of power was used to move a 50 kg rock 50 m in 30 s. How much work was needed and how much force was used to accomplish this? The rock then fell 75 m off a cliff, what wasits
gravitational potential energy of the rock at the top of the cliff? What was its speed just before therock
hit the ground at the bottom of the cliff?

As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.

Light traveling in a medium with a refractive index 1.19 is incident on a plate of another medium with index of refraction 1.79. at what angle of incidence is the reflected light fully polarized?

Heating water for hot cocoa while sitting next to a campfire can be examples of conduction, convenction and radiation at the same time agree disagree it depends how you know