Questions
(1).

0.04 kg of carbon dioxide (molecular weight = 44) is compressed from 1 bar,20°C, until the pressure is 9 bar, and the volume is.. Calculate the change of entropy.Take cpc_p for carbon dioxide as 0.88 kJ/kg K, and assume carbon dioxide to be a perfect gas

(2).

300 kJ/s of heat is supplied at a constant fixed temperature of 290°C to a heat engine. The heat rejection takes place at 8.5°C. The following results were obtained.

(3).

3-Hinge Gable Frame Given: The 3-hinge gable frame shown in the diagram Determine: The shear and moment diagrams.

(4).

400 V, 3-phase, 50 Hz, 6 pole induction motor is supplying a load of 20 kW, when the frequency of rotor currents is 2Hz. Estimate (i) Slip and speed at this load (ii) Rotor copper loss (iii) Speed of motor when supplying 30 kW load assuming torque-slip curve to be a straight line.

(5).

4-pole, 50 Hz, 3-phase 400 V induction motor develops 20 KW including mechanical losses when running at 1440 rpm and the p.f is 0.8. Determine (i) rotor current frequency (ii) total input if the stator loss is 1000 W (iii) the line current.

(6).

500 kJ of heat is removed from a constant temperature heat reservoir maintained at 835 K. Heat is received by a system at constant temperature of 720 K. Temperature of the surroundings, the lowest available temperature is 280 K. Determine the net loss of available energy as a result of this irreversible heat transfer.

(7).

6% of the power supplied to a cable appears at the output terminals. Determine the power loss in decibels.

(8).

A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low-pass filter with cut-off frequency 800 Hz. The output signal has the frequency.

(9).

Show that the evolution equation of a harmonic oscillator of mass M, subjected to an elastic force Fel and free of friction, is invariant under time reversal.

(10).

The orbital path of another satellite is shown in the sketch. In which positions A through D does the satellite have the greatest KE? The greatest PE? The greatest total energy?