You want to build a generator to light a bulb. You have a fairly large permanent magnet, some wire, and a lightbulb. You may build it as follows. Wind the wire for about 200 turns into a coil of 15 cm radius. Tape up the coil and place it in the region between the poles of the magnet that produces a 0.10 T magnetic field. Connect a hand crank to the coil and rotate it at a rotational speed ω. What is the required rotational speed ω to generate a peak voltage of 6 V?

The passing of heat through a material while the material itself stays in place. a. radiation b. conduction c. convection

Classify each possible hypothesis about a medicinal aloe vera plant as falsifiable or non-falsifiable. aloe vera gel is the best natural skin moisturizer. aloe vera gel can heal wounds by boosting cell renewal. aloe vera juice tastes better than carrot juice. drinking aloe juice can reduce the risk of lung cancer.

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.