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(a) Find a conversion factor to convert from miles per hour to kilometers per hour.
(a) Find a conversion factor to convert from miles per hour to kilometers per hour. (b) In
the past, a federal law mandated that highway speed limits would be 55 mi/h. Use the
conversion factor of part (a) to find this speed in kilometers per hour. (c) The maximum
highway speed is now 65 mi/h in some places. In kilometers per hour, how much increase
is this over the 55 mi/h limit?
1. The velocity of a train changes from 0 to 60 in 20 seconds. Assuming that it is uniformly accelerated, what is the acceleration in m/s squared?
Assume 5 lb/sec of fluid enter a steady state, steady flow system with p1 = 100 psia, 1 =
0.2 lb/ft3
, v1 = 100 fps, u1 = 800 Btu/lb and leave with p2 = 20 psia, 2 = 0.05 lb/ft3
, v2 = 500
fps, u2 = 780 Btu/lb. During the passage through the open system, 10 Btu/lb of heat is
rejected. Find the work in hp.
A steady flow, steady state thermodynamic system receives 45 kg/min of a fluid at 207kPa
and discharges it from point 24 m. above the entrance section at 1034 kPa. The fluid
enters with a velocity of 36.6 m/s and leaves with a velocity of 12 m/s. During this process,
there are supplied 7 kW of heat from an external source, and the increase in enthalpy is
4.6 kJ/kg. Determine the work in kW and in horsepower.
Steam enters a turbine stage with an enthalpy of 3628 kJ/kg at 70 m/s and leaves at the
same stage with an enthalpy of 2846 kJ/kg at 124 m/s. Calculate the work per kg done by
the steam.
Steam with a flow rate of 1360 kg/h enters an adiabatic nozzle (adiabatic, Q=0) at 1378
kPa, specific volume of 0.147 m3
/kg, and specific internal energy of 2510 kJ/kg. The exit
conditions are 137.8 kPa, 1.099 m3
/kg specific volume, and 2263 kJ/kg of specific internal
energy. Find the exit velocity.
In a steady flow apparatus, 135 kJ of work is done by each kg. of fluid. The specific volume,
pressure, and velocity of the fluid at the inlet are: 0.37 m3
/kg, 600kPa, and 16 m/s. At the
outlet are: 0.62 m3
/kg, 100 kPa, and 270 m/s. The inlet is 32 m. above the discharge line.
The heat loss between the inlet and discharge is 9 kJ/kg. In flowing through this apparatus,
does the specific internal energy increases or decreases?
Air flows steadily at the rate of 0.5 kg/s through an air compressor, entering at 7 m/s, 100
kPa, 0.95 m3
/ kg specific volume, and leaving at 5 m/s, 700 kPa, and 0.19 m3
/kg specific
volume. The internal energy of the air leaving is 90kJ/kg greater than that of the air
entering. Cooling water in the compressor jackets absorb heat from the air at the rate of
58 kJ/s. Calculate the work.
An elevator in on the thirtieth floor of an office building when supporting cables shears.
The elevator drops vertically to the ground where several springs absorb the impact of the
elevator. The elevator mass is 2500 kg and it is 100 m. above the ground. Determine: a)
the potential energy of the elevator before its fall, b) the velocity and kinetic energy the
instant before the impact.
