Two protons are a distance 4. 10-9 m apart. What is the electric potential energy of the system consisting of the two protons? (J) 2. A proton and an electron are a distance 4. 10-9 m apart. What is the electric potential energy of the system consisting of the proton and the electron?(J) Which of the following statements are true? If any two charged particles are released from rest, they will spontaneously move in the direction in which the potential energy of the system will be decreased. In some situations charged particles released from rest would move in a direction that increases electric potential energy, but not in other situations. If released from rest two protons would move closer together, increasing the potential energy of the system. (can be more than one!) please help me due tonight!

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.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

You have a resistor and a capacitor of unknown values. first, you charge the capacitor and discharge it through the resistor. by monitoring the capacitor voltage on an oscilloscope, you see that the voltage decays to half its initial value in 2.70 miss . you then use the resistor and capacitor to make a low-pass filter. what is the crossover frequency fc?