An electron with a speed of 2.3 ×106m/s collides with an atom of element x. shortly afterward, the atom emits a 1240 nm photon. what was the electron's speed after the collision? assume that, because the atom is so much more massive than the electron, the recoil of the atom is negligible. hint: the energy of the photon is not the energy transferred to the atom in the collision.

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.

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Select the three ways that the parallel-plate capacitor differs from a car battery.