Section A Complete all five questions in this section. Marks will be given for working and structure as well as for numerical answers.
MarksA1From measurements taken at two points on the compression curve of an oil engine indicator diagram, as shown, the following data are recorded:①pressure 140 kn/m², volume 12 litres②pressure 2·8 MN/m², volume 1·2 liters(a)Determine the polytropic index, n, for the curve between the two points and, hence:3(b)Calculate the work done between the two points.4(c)Assuming a temperature of 100°C at the first point, determine the temperature at the second point.3Take J/kgK717·0,kJ/kgK287·0
VCR Total Marks in A110A2The temperature of a gas streamis to be measured by a thermocouple whose junction can be approximated to a 1·2 mm-diameter sphere. The properties of the junction are:J/kg K,320andkg/m8500,W/mK353
p Ck.
The heat transfer coefficient between the junction and the gas is W/m²K65
h10Determine how long it will take for the thermocouple to read 99% of the initial temperature difference.Total Marks in A210A3Consider two identical bodies, one at 5000 K and the other at 2000 K. With the aid of a suitable diagram, explain:
(a)Which of the two bodies will emit more radiation in the shorter-wavelength region.8
(b)Which of the two bodies will emit more radiation at a wavelength of 20 μm.2Total Marks in A310NB .
