A person is diving in a lake in the depth of h = 5.5 m. The density of the water is rho = 1.0 x10^3 kg/m^3. The pressure of the atmosphere is P0 = 1.0 x 10^5 Pa. The surface area of the top of the person's head is A = 0.046 m^2.
(a) Express the absolute pressure at the depth of h, P, in terms of P0, rho, and h.
(b) Calculate the numerical value of P in Pa.
(c) Express the magnitude of the force exerted by water on the top of the person's head F at the depth h in terms of P.
(d) Calculate the numerical value of F in N.

Avery hard rubber ball (m = 0.5 kg) is falling vertically at 4 m/s just before it bounces on the floor. the ball rebounds back at essentially the same speed. if the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

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.