Engineering Science N2
ENGINEERING SCIENCE N2 QUESTION PAPER
AUGUST 2012
Here are the answers to this question paper:
Question 1
1.1 27,5 m/s = 99 km/h
1.2 graph
1.2.1 a = 5,5 m/s^2
1.2.2 s = 68,75 m
1.2.3 s in 20 s = 11 m
1.4 Distance = 150 m
1.4.1 Displacement = 111,803 m
Direction = S 71,565 degrees E or 71,565 deg E of S
Question 2
2.1 The Resultant of a system of forces is that single force that can replace the system of forces, and produce the same result as the system of forces.
2.2 Beam
2.2.1 F = 12,5 kN
2.2.2 L = 17,5 kN
2.3 F = 69,738 N
2.4 Turning point is in the centre, 0,75 m from either end.
Question 3
3.1 Potential Energy is the energy a body possesses due to its mass and height above a reference plane.
3.2
3.2.1 t = 2,041 s
3.2.2 PE at highest point = 3257,99 J
3.2.3 Velocity at ground level = 32,954 m/s
3.2.4 Momentum at ground level = 197,724 kg-m/s
Question 4
4.1 Power is the rate at which work is being done.
4.2
4.2.1 Graph
4.2.2 Total weight of cable = 5250 N
4.2.3 Work done = 1 841 875 J or 1,841875 MJ
4.2.4 Power = 106 kW
Question 5
5.1 Belt drives have the following advantages over gear drives:
- Lubrication requirements are simplistic, as only the pulley bearings need to be greased.
- Power can be transmitted with shafts at large centre distance apart.
- Belts are cheaper to maintain and/or replace than gears.
5.2
5.2.1 Actual load = 4050 N
5.2.2 Displacement Ration (Velocity Ratio) = 48
5.2.3
5.3
5.3.1 Effective force = 440 N
5.3.2 Power = 3 455,752
5.4 Sketch of differential wheel-and-axle
Question 6
6.1
6.1.1 depth = 81,633 m
6.1.2 Pabs = 921,3 kPa
6.2
6.2.1 false
6.2.2 true
6.3
6.3.1 W para = 920,164 N
6.3.2 W perp = 1730,577 N
6.3.3 Friction force = 920,164 N
6.3.4 Coefficient of friction = 0,532
Question 7: Heat
7.1 When 1 kg of the coal is combusted, 30 MJ of heat energy will be released.
7.2
7.2.1 Heat per hour = 270 MJ
7.2.2 final temp of water = 90,233 deg celsius
7.3 final temp = 73,824 deg celsius
7.4 An increase in pressure increases boiling point, and vice versa.
Question 8
8.1
8.1.1 A molecule is a chemical combination of two or more atoms, from the same or of different elements.
8.1.2 An ion is an atom which has either lost or gained electrons.
8.2 electrons - negative
protons - positive
neutrons - neutral
8.3 Electroplating is used to :
- beautify a plain metal (such as mild steel) with a shiny coating of an expensive metal, such as silver or gold
- protect metals againt rust
