Aman uses a lever jack to lift a 2.00 x 10^3 kg car to change a tire. each stroke of the jack lifts the car a distance of 5.00 x 10^-3 m. the vertical displacement of the handle is 0.75 m for each stroke. how much total force does he use with each stroke of the jack?

a) 19,600 n
b) 3.0 x 10^5 n
c) 131 n
d) 2.9 x 10^6 n

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.

Two technicians are discussing a resistance measurement between the can-h and can-l wires. technician a says this measurement should be done with the ignition switch in the "run" position. technician b states that a measurement of 0 ohms indicates an open in the network. which technician is correct?

What do you think car designers do if the damage caused by a crash test is too severe?