Molecular Physics | Thermodynamics Answers

Air enters a gas turbine system with a velocity of 105 m/s and has a specific volume of 0.8m3 /kg. The inlet area of the gas turbine system is 0.05m2. At exit the air has a velocity of 135m/s and has a specific volume of 1.5 m3 /kg. In its passage through the turbine system, the specific enthalpy of air is reduced by 145kJ/kg and the air also has a heat transfer loss of 27 kJ/kg. Determine: (a) The mass flow rate of the air through the turbine system in kg/s? (b) The exit area of the turbine system in mạ ? (c) The power developed by the turbine system in kW?

A drum 0.5 ft in diameter and 45 inches long contained acetylene at 350 psia, 90 o F. After some of the

acetylene was used, the pressure was 200 psia and 85 o F. a) determine the amount of acetylene that

was used (lb m ). b) What volume would the used acetylene occupy at 14.7 psia, 80 o F (ft 3 ) ? R for this

gas is 59.35 ft-lb f /lb m- R.

A body starts from an origin with initial velocity and moves along the x-axis. Derive an expression for the final velocity v of the distance covered.
B). A train passes a station A at 40kmh-¹and maintain this speed for 10km and is then uniformly retarded stopping at the same time as the first train.
I. On the same diagram sketch the velocity time graph for the two trains.
ii. Find the greatest speed of the second train on the journey.  

A cable exerts a constant upward tension of magnitude 2.26 ✕ 10⁴ N on a 2.00 ✕ 10³ kg elevator as it rises through a vertical distance of 3.50 m.

(a) Find the work done by the tension force on the elevator (in J).

___ J

(b) Find the work done by the force of gravity on the elevator (in J).

 ___J

A vector located in the second quadrant has an x-component of -80 m at an angle of 20°, as shown. Find the magnitude of the vector and its y-component.

Four sled dogs are pulling a 1000kg load, Sled dog A is pulling the load at 20 N, 10° north of east. Sled dog B is pulling the load at 55 N, 70° north of east. Sled dog C is pulling the load at 45 N, 33° north of west, while sled dog D exerts 30 N at a direction of 80° south of west. What is the resultant force acting on the load?

Steam enters a turbine with an enthalpy of 1292 BTU/lb_m. The transferred heat is 13 BTU/lb_m. What is the work in BTU/min and in hp for a flow of 2lb_m/sec?

A reciprocating compressor draws in 500 ft₃/min of air whose density is 0.079lbm/ft₃ and discharges it with density of 0.304lbm/ft₃. At the suction, р₁ = 15 psia, at the discharge, р₂ = 80 psia. The increase in the specific internal energy is 33.8 BTU/lb_m. Determine the work on the air in BTU/min and in hp. Neglect change in kinetic energy.

8. Calculate the heat transfer rate per m2 area by radiation between the surfaces

of two long cylinders having radii 100 mm and 50 mm respectively. The smaller cylinder being in the

larger cylinder. The axes of the cylinders are parallel to each other and separated by a distance of

20 mm. The surfaces of inner and outer cylinders are maintained at 127°C and 27°C respectively. The

emissivity of both the surfaces is 0.5.

Assume the medium between the two cylinders is non-absorbing.

Three thin walled infinitely long hollow cylinders of radii 5 cm, 10 cm and

15 cm are arranged concentrically as shown in Fig. 15.54. T1 = 1000 K and T3 = 300 K.

Assuming ε1 = ε2 = ε3 = 0.05 and vacuum in the spaces between the cylinders, calculate the

steady state temperature of cylinder surface 2 and heat flow per m2 area of cylinder 1