You are at the controls of a particle accelerator, sending beam of 3.90 x 10^7 m/s protons (mass m) at a gas target of an unknown element. your detector tells you that some protons bounce straight back after a collision with one of the nuclei of the unknown element. all such protons rebound with a speed of 3.60 x 10^7 m/s. assume that the initial speed of the target nucleus is negligible and that the collision is elastic.

(a) find the mass of one of the nuclei of the unknown element. express you answer in terms of the proton mass m.
(b) what is the speed of the unknown nucleus immediately after such a 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.

A2k pendulum has a speed of 1 m/s at a height of 1/2 meter

Aphoton is absorbed by an electron that is in the n = 3 state of a hydrogen atom, causing the hydrogen atom to become ionized. very far away from the nucleus, the released electron has a velocity of 750,000 m/s. what was the wavelength of the absorbed photon?