Two people hold opposite ends of a rope of length of 10.00 m and mass 156 g. One person exerts a force of magnitude 40.0 N and the rope is stationary. A brief interval Dt after one person initiates a pulse the second person does the same. The two pulse meet 1.0 m away from the center of the rope. What was the time interval Dt between initiation of the pulses

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 a hiker that weighs 600 newtons climbs a 50 meter hill, how much gravitational potential energy has the hiker gained?

Why do atoms emit energy of only specific wavelengths