A pencil falls from 1.25m tall table. It rolls at a rate of .5m/s. How long will the pencil be in the air.

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.

Inside of a windmill or a dam is a that is used to transform one type of energy into electrical energy. a. motor b. generator c. transformer d. power pack

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat