7. Define Efficiency in words. How efficient are cars compared to bicycles, why do you think bicycles are more
efficient? (Hint: Explain using the wasted energy in each case)
8. A food blender takes in 300J of electrical energy gives out only 100J of mechanical energy.
a. Explain how energy transforms in a food blender and the kinds of energy that are wasted (unusable).

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

An object is located 30.0 cm from a concave mirror. the focal length is 15.0 c,. what is the image distance? a. 30.0 cm b. -10 cm c. 10.0 cm d. -30.0 cm

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.