s SCHOOL OF COMPUTING, ENGINEERING AND MATHEMATICS SEMESTER EXAMINATIONS 03/04 FY04 Engineering Science Time allowed: TWO hours Answer: All SEVEN questions Questions do not carry equal marks The total number of marks is 00 Items permitted: Any approved calculator Items supplied: Formula sheet Data sheet Linear graph paper Marks for whole and part questions are indicated in brackets ( ) FY003_03/04 Page of 6 Printing date: 0/0/04
Question A black-body radiator is heated from 300 K to 3000 K. Describe the changes in radiant energy output and appearance of the body as it is heated; (a) by means of relevant formulae and diagrams. (b) in terms of 'colour temperature'. (c) in terms of changes in the radiant spectrum and intensity during the heating operation. Question A Gatso speed enforcement camera transmits a RADAR beam at a frequency of 4.0 GHz. A number of vehicles pass the camera. The camera receives a series of signals at different frequencies reflected back from the vehicles. a) What will be the transmitted RADAR wavelength? b) Calculate the frequency of the received signal and the speed of the vehicle for a frequency shift of +6.46 khz. Your answer should also comment on the direction of travel of the signal. c) A car travels at 50 kph away from the Gatso camera. Determine the frequency of the signal that would be received by a RADAR detector in the car? Question 3 Draw a pressure vs. temperature phase diagram for carbon dioxide. Mark on the diagram, all phases, phase boundaries, the critical point and the triple point. (6 marks) a) What is meant by the triple point of a substance? b) What is meant by the critical point of a substance? c) Indicate clearly the position on the diagram that would represent the state when the carbon dioxide is inside a full fire extinguisher at room temperature. (3 marks) FY003_0/03 Page of 6 Printing date: //0
Question 4 (a) What is meant by the terms additive and subtractive colourimetry? Include in your answer the differences between Electric Magenta (Additive secondary Magenta) and Process Magenta (Printers Magenta). Give examples of each process. (0 marks) (b) Why does Magenta not appear in the visible electromagnetic spectrum? (c) Explain in terms of a trichromatic system why fully saturated cyan cannot be displayed on a television or computer screen. Question 5 A nf air capacitor is formed of two metal plates, each of area 0.4 m. (a) How far apart are the plates of the capacitor? (b) A current of 0.3 ma flows into the capacitor. Calculate the minimum time the current needs to flow for the capacitor to be charged to 00V. (c) Consider a charged particle located between the plates of the capacitor. Determine the charge on the particle if the magnitude of the force that the particle experiences is 4N. Question 6 A ray of light strikes a 30mm thick glass block at an angle of incidence of 30 o and passes through the block. If the refractive index of the glass block is.5; (a) What is the apparent speed of the light in the glass? (b) What is the angle of refraction of the ray of light? (c) By how much has the ray of light been displaced sideways as it leaves the block? FY003_0/03 Page 3 of 6 Printing date: //0
Question 7 A large aluminium pan of water at 00 C sits on an aluminium cylinder of diameter 0.3m and height of 0. m. The cylinder in turn sits on a hot-plate maintained at a temperature of 00 C. The base of the pan is 5mm thick. Assume that it is slightly larger than the diameter of the cylinder. (a) Determine how much heat is transferred from the hot plate to the water in 00 seconds. (b) Calculate the mass of water that is boiled away in another 0 seconds. State all assumptions made. FY003_0/03 Page 4 of 6 Printing date: //0
FORMULA SHEET V = IR W = IV W= V /R W = I R Q = It F = ma v = u + at s = ut + ½at² s = ½(v + u)t v² = u² + as Q = VC v = f T = /f T p V p V c μ T T E = m g h (Potential Energy) E = ½ mv (Kinetic Energy) m v = m v Towards Away c vr c vr f o fs f o fs c vs c vs f f o d Vt c Hz = f E = m L E = ½ I (Kinetic Energy) L = I (Angular momentum) I = mr (Moment of Inertia) (Newton s nd Law) T L g n Sin θc n F. 4πε 0 Q Q r f u v m u v g = 9.8 ms - 0 = 8.85 x 0 - F m - c = 3 x 0 8 ms - e =.788 σ = 5.67 x 0-8 Wm - K -4 H = 6.6606957 0-34 m kgs - Speed of sound = 330 ms - ε 0 ε A r C d v F = EQ E d A E = m C T 4 - T 4 Q θ -θ λ A t x R L n = sinѳ A sinѳ s = t sin (θ i θ r ) cosθ r V peak = NAB F = BIl R eq = R + R + R 3 + R n... R R R R R eq Colour Value Multiplier Tolerance Black 0 x Brown x0 % Red x0 % Orange 3 x0 3 Yellow 4 x0 4 Green 5 x0 5 Blue 6 x0 6 Violet 7 x0 7 Grey 8 x0 8 White 9 x0 9 Gold x0-5% Silver x0-0% For a Sine wave Vpk Vrms Sin θ Cos θ Tan θ 3 Opposite Hypotenuse Adjacent Hypotenuse Opposite Adjacent H n C FY003_0/03 Page 5 of 6 Printing date: //0
DATA SHEET Specific heat capacities:- Water 4.8 kj kg - K - Aluminium 0.897 kj kg - K - Ice. kj kg - K - Additional data:- Latent heat of fusion of water 334 kj kg - Latent heat of vaporization of water.6 x 0 6 J kg -, Thermal conductivity of aluminium 5 W m - K - Thermal conductivity of iron 80 W m - K - The density of water kg per litre. FY003_03/04 Page 6 of 6 Printing date: 0/0/04