QUESTION 1

Diagram 1.1 shows a cooling system of a motorcycle engine.You as a mechanical engineer are given a task to study characteristics of metal shown in the Table 1.2 to be used as effective fins in the cooling system of the motorcycle engine.

[ 10 marks ]

1

Types of metal Specific Heat CapacityJ kg-1°C-1

Melting point°C

Heat Conductor Rate of expansion

P 300 1020 Good ModerateQ 360 700 Moderate HighR 450 1600 Good ModerateS 900 720 Moderate High

Diagram 1.1

QUESTION 2

2

A student plans to fix a lamp in his room. Table 3 shows the features of 4 different types of lamps.

Type of lamp Power Efficiency Life Span Price

Compact fluorescent lamp

18 W 50 % 7000 hours High

Filament lamp 75 W 12 % 1000 hours Low

Long fluorescent lamp 20 W 45 %14000 hours

Medium

Round fluorescent lamp 24 W 40 %10000 hours

High

Explain the suitability of each feature in Table 3 and then determine the most suitable lamp to be used. Give a reason for your choice.

[10 marks]

3

QUESTION 6

4

Table 6 shows the specifications of four water storage tanks, P, Q, R and S, that can be used to store

Water storage tank P Q R S

Material used metal concrete concrete metal

Density

low high low low

ShapeBentuk

Height from the ground

low high high low

Table 6

You are required to determine the most suitable water storage tank. Study the specifications of all the four water storage tanks based on the following aspects :

- The material used

- The density of the tank

- The shape of the tank

- The height of the tank from the ground

[10 marks]

QUESTION 7

Table below shows the characteristics of four types of cables that have the same length.

Cable Diameter/ cm Density/ kgm-3 Rate of expansion Melting point

P 2 4.50 x 103 Medium High

Q 4 3.00 x 103 Low High

R 3 5.45 x 103 High Low

S 1 2.50 x 103 Low Medium

You are to choose one of the cables to be used in the National Grid Network. Explain the suitability of each of the characteristics of the cables. Choose the most suitable cable and justify your choice.

[10 marks]

5

QUESTION 9

The transmission of electricity over the National Grid Network uses high voltage cables. You are assigned to study the characteristics of cables which could be used as transmission cable. Table 12 shows the characteristics of four transmission cables.

Cable Resistivity /Ωm-1 Density / kg m-3 CostRate of thermal

expansion

P 3.0 x l0-7 5 x l05 LowHigh

Q 1.8 x l0-8 2 x l03 MediumLow

R 7.5 x l0-7 8 x l02 HighMedium

S 7.0 x l0-8 4 x l03 MediumHigh

Table 10

Based on the table 10;

(i) Explain the suitability of the characteristics of the cables to be used as transmission cable.

(ii) Determine the most suitable transmission cable to be used and give reasons for your choice.

[10 marks]

QUESTION 10

You are required to build a hydrometer that can be used to measure densities of concentrated acids.

Table 11 shows the characteristics of 4 types of hydrometers L, M, N and O.

HydrometerType of

material of hydrometer

Diameter of capillary tube/ cm

Density of shots/ kgm-3

Diameter of bottom bulb/ cm

L Plastic 0.5 1000 1.0M Plastic 2.0 1300 3.0N Glass/ 0.5 9800 3.0O Glass 2.0 8000 1.0

Table 11

Based on the table 11(i) Explain the suitable characteristics of the hydrometer so that it can be used

to measure different densities of acids.

(ii) Decide which hydrometer is most suitable and give reasons. [10 marks]

6

QUESTION 11

Heat generated in the car engine has to be removed effectively to avoid overheating. Diagram 12.1 shows the cooling system of a car engine

Diagram 12.1

Table 12.1 shows the characteristics of liquid that can be used in the cooling system of a car.

Liquid

Characteristics

Specific heat capacity( J kg-1 °C-1 )

Freezing point(°C)

Boiling point(°C)

Rusting rate of metal

J 5000 20 110 High

K 4600 -15 120 Low

L 3800 15 95 Medium

M 3000 5 95 Medium

N 200 -20 320 Low

You are asked to investigate the characteristic of the liquid in Table 12.1 which could be used in cooling system of a car. Explain the suitability of each characteristic in Table 12.1 and hence, determine which liquid is most suitable to be used in the cooling system.. Justify your choice. [ 10 marks ]

Cooling jackets

Heater hoses

Heater core

Water pump

Down-flow radiator

Lower radiator hose

thermostat

Bypass hose

Coolant recovery system

Upper radiator hose

7

QUESTION 12

8

As a sport officer, you are given the responsibility to design a high jump landing pad. Table 12 shows four types of foam materials with different specifications.

Type of material

Density /

kgm-3

Elasticity /

N cm-1

Thickness / cm

Rate of air absorption

P 1500 15.2 60.0 HighQ 1700 13.5 45.0 LowR 1200 13.7 80.0 HighS 2000 16.0 85.0 moderate

Table 12

You are required to determine the most suitable material to be used to make the landing pad. Study the specifications of all the four types of material from the following aspects:

- The density of the material- The elasticity of the material- The thickness of the foam- The ability to absorb water of the material

Explain the suitability of the aspects. [10 marks]

QUESTION 14

9

Diagram 14 shows circuits P, Q, R, S and T each containing an ideal transformer. Diodes in the circuits are used for the purpose of rectification.

Circuit Specification of circuit

P

Q

R

S

T

You are asked to make a circuit that can be used to switch on 12 V d.c. radio. Study the circuits P, Q, R, S and T in Diagram 12.1 and consider the following aspects:

- type of transformer- ratio of the number of turns in primary coil to secondary coil- type of rectification- characteristic of output current

Explain the suitability of the above aspects and hence, determine the most suitable circuit to switch on 12 V d.c. radio. Justify your choice.

[ 10 marks ]

QUESTION 15

10

Diagram 15.1 shows a pair of outdoor shoes suitable for mountain trekking.

Diagram 15.1 Table 15.2 shows the characteristics of five types of materials that can be used for makingthe soles of the trekking shoes.

Table 15.2

You are asked to study the characteristics of the materials shown in Table 15.2. Explain the suitability of each characteristic in Table 11.1 and then determine the most suitable material to be used. Give a reason for your choice.

[ 10 marks ]

Type ofmaterial

Density(Kg/m -3)

Number of studs x Area of 1 stud

Expansion effect

Ability to stretch

P 820 6 x 30 cm2 Low Good

Q 700 8 x 30 cm2 Low Good

R 720 5 x 30 cm2 Medium Average

S 750 4 x 30 cm2 High Poor

T 880 3 x 30 cm2 High Poor