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QUESTION 1 What is the gear ratio of this worm and wheel? (A) 1:6 (B) 6:3 (C) 18:1 (D) 18:3
QUESTION 2 8) A 25 kg block is pulled up an incline using a force P as shown. What is the minimum value of P required to just move the box from rest if the coefficient of static friction is 0.4? (A) 192.3N (B) 103.5N (Cc) 414N (D) 14.7N
QUESTION 7 A 20 kg box sits just on the point of sliding on an incline plane. If the coefficient of static friction is 0.27 what is the angle of repose? (A) 5 (B) 13 (Cc) 15 (D) 16
QUESTION 9 A bicycle has gearing with a VR of 1:3. The rear tyre has an outside diameter of 740 mm. What is the distance travelled for every three rotations of the foot pedals? (A) 42m (B) 21m (Cc) 7m (D) 2m Engineering
QUESTION 15 (6 marks) Explain why an engineer would recommend solar-powered water pumps for crop irrigation to a community in a developing country. For three different types of technology knowledge identify two factors of each to support your explanation.
QUESTION 16 (5 marks) platform e The 15-tooth gear A drives a gear train used to raise a platform a distance of 1.2 m. The teeth of gear C have a pitch of 10 mm and gear B has 30 teeth. Identify the gear train used and determine the ratio of gear A to gear C. Explain your reasoning. Not drawn to scale
QUESTION 18 (5 marks) A 900 kg machine is designed to rest without slipping on a slope of up to 30° on the surface of Mars. The acceleration due to gravity on Mars is one-third of that on Earth. a) Determine the coefficient of static friction required to keep the machine from slipping on a 30° incline on Mars. Answer to two decimal places. [1 mark] b) Calculate the resulting force of static friction between the machine and Mars` surface. Answer to the nearest whole unit. [2 marks] c) Explain what would happen to the coefficient of static friction if the machine was tested on Earth. [2 marks]
QUESTION 19 (6 marks) A crane requires 4355 W to vertically lift a full scrap metal bin a distance of 20 m from the ground at constant velocity over a period of 90 s. a) Determine the mass of the full scrap metal bin to the nearest whole unit. [3 marks] b) Determine the velocity on impact of a 5 kg section of scrap metal that falls to the ground unobstructed from the bin at the top of the lift. Answer to the nearest whole unit. [3 marks]
QUESTION 22 (9 marks) A bag slides for 3 seconds at a constant velocity of 1 m/s down a 20° luggage chute until it impacts with a cushioning device as shown in the diagram. If the cushioning device is removed the surface of the chute will need to be modified to slow the bag to a stop at the base of the chute. Not drawn to scale Determine the difference between the coefficients of friction for the modified chute and the original with the cushioning device. Answer to two decimal places.
QUESTION 23 (6 marks) An elevator starts from rest and accelerates upwards at a constant rate until the desired velocity of 10 m/s is achieved. The mass of the elevator and occupants is 2500 kg. The tension on the elevator cable 1s 30 000 N. Determine the distance the elevator travels during acceleration to the nearest whole unit (m). Include a force diagram with your working.
QUESTION 4 5) Not to scale A box slides down a slope as shown. If the coefficient of friction between the box and the slope is 0.2 what is the acceleration of the box? (A) 8.0 m/s (B) 4.1 m/s? (C) 2.4m/s? (D) 1.8 m/s?
QUESTION 5 Not to scale This crane vertically lifts a load a distance of 20 m using a pulley system. What distance must the main winch cable move during the vertical lift? (A) 100m (B) 80m (C) 20m (D) 5m
QUESTION 6 A crowbar is used to lever a floorboard as shown. An effort of 55 N is applied to the crowbar at position P generating a force of 550 N that raises the floorboard by 20 mm. If the crowbar displacement Q is 700 mm what is the efficiency of the crowbar? \ Not to scale (A) 79% (B) 36% (C) 29% (D) 10%
QUESTION 7 A pulley system with an efficiency of 75% is used to vertically raise a 120 kg load a distance of 3 m. If the length of pulley rope pulled to raise the load is 8 m the effort required is (A) 330N. (B) 392N. (C) 440N. (D) 588N.
QUESTION 9 The work done by a jack to vertically raise a 1500 kg vehicle a distance of 180 cm is (A) 2700 J. (B) 8167 J. (C) 26 460 J. (D) 81667).
QUESTION 12 (4 marks) State four fields of knowledge used by a biomedical engineer to perform their role. l. 2 3. 4
QUESTION 16 (5 marks) This simple machine is used by turning handle A to raise a 10 kg bucket of water from a 10 m deep well. The hand-operated handle A has a turning circle of 1 m and the lifting arm B has a diameter of 250 mm. The machine takes 30 seconds to raise the water. Explain the work done by the machine and the power used to lift one bucket of water. Use mathematical reasoning to support your explanation. Not to scale
QUESTION 17 (6 marks) Describe a community problem related to a sustainability issue. Explain how engineers have used their knowledge to develop a solution for this problem and how the solution has reduced the environmental impact to provide two benefits for the community involved.
QUESTION 20 (5 marks) A 500 kg piledriver is used to drive a 200 kg pile into the soil as shown. The piledriver falls freely through a distance of 4 m before impacting the pile with 19.6 kJ of energy. At the moment of impact energy is lost as heat and sound. Nottoscale _@ ~~ a) If5.4kJ of energy is lost during the impact between piledriver and pile determine the velocity of the piledriver just after impact. Answer to two decimal places. [3 marks] b) Ifthe pile and piledriver decelerate at a constant rate of 30 m/s after impact due to the resistance of the soil determine the distance the pile is driven into the ground. Answer to the nearest whole unit (mm). [2 marks]
QUESTION 21 (5 marks) A bucket is used to carry iron ore vertically up a mine shaft from its base. The bucket is raised from rest at the base of the shaft and accelerates constantly upwards at a rate of 0.75 m/s for 4 s. It then travels at a constant velocity before decelerating constantly to stop at the top of the shaft. a) Determine the maximum velocity of the bucket to the nearest whole unit. [3 marks] b) From rest the bucket is lowered from the top of the shaft with a constant acceleration. Determine the buckets acceleration if the bucket has been lowered 25 m after 10 s. Answer to one decimal place. [2 marks]
QUESTION 22 (6 marks) This winch crane is driven by an electric motor. The motor drive shaft is fitted to a 15-tooth gear A which drives a 100-tooth gear B attached to a cable drum. The 500 mm diameter cable drum houses a steel cable that is used to vertically raise 20 kg hay bales 2 m from the ground to be loaded onto trucks. Cable drum + Drum drive p oo Motor drive a gear A Not to scale a) Calculate the output power of the crane if it takes 30 seconds to raise two hay bales. Answer to two decimal places. [2 marks] b) Determine the number of motor revolutions required to produce the 2 m lift. Answer to one decimal place. [4 marks]
QUESTION 23 (10 marks) A conveyor transfers a 2 kg component between two assembly points during a product manufacturing process. Initially stationary at assembly point 1 the component moves 10 m with a uniform acceleration of 2 m/s just without slipping on the conveyor to assembly point 2 where it stops. Determine the coefficient of static friction required between the conveyor and the component if the transfer time between the two assembly points is reduced by 20%. Answer to two decimal places.
QUESTION 3 During a race the rear wheels of a go-kart exert a horizontal force of 100 N on the racetrack surface when the rear axle is rotating at 1000 revolutions per minute (rpm). The wheels have a diameter of 280 mm. The power being transmitted to the track by the rear wheels is (A) 88kW (B) 2.9kW (C) 15kW (D) 0.73 kW
QUESTION 4 A scissor jack is used to lift a 1.5 tonne vehicle. This content has not been published for copyright reasons. If the 2.5 mm pitch of the central screw allows the vehicle to be raised 5 mm during one revolution of the handle the velocity ratio of the jack is (A) 40:1 (B) 126:1 (C) 251:1 (D) 300:1
QUESTION 5 A pump transfers water vertically up to a cylindrical water tank sitting on a platform 7 m above the ground. The tank is 3 m deep and holds 20 kL when full. Given that | L of water has a mass of | kg the potential energy of the full tank at its vertical midpoint relative to a water outlet 1 m above ground level is (A) 1.47MJ (B) 1.67 MJ (C) 1.76 MJ (D) 1.86 MJ
QUESTION 7 A 10 kg wheelbarrow sits stationary but just on the point of sliding on an inclined ramp. When the ramp is raised by 5 to make an angle of 20 to the horizontal the wheelbarrow slowly starts to slide. The minimum amount of additional force required to stop the wheelbarrow from sliding is (A) S59N (B) 34N (C) 25N (D) 8N
QUESTION 9 A mechanism extends an initially stationary rod 15 mm at a final velocity of 2.5 m/s. The acceleration of the rod is (A) 417 m/s? (B) 208 m/s (C) 38 m/s? (D) 21 m/s
QUESTION 10 A diagram of a steam-driven engine is shown. This content has not been published for copyright reasons. When the steam engine is in motion the movement of the piston rod is (A) oscillating. (B) reciprocal. (C) rotary. (D) linear.
QUESTION 11 (5 marks) Explain the concepts of mechanical advantage and velocity ratio using a simple pulley system. Provide an annotated sketch to support your response.
QUESTION 18 (5 marks) Determine the force required to launch a rocket with a mass of 2000 kg vertically from rest to a height of 20 km 1n 20 seconds. Assume that the rocket`s mass and acceleration due to gravity remain constant during the launch and that air resistance is not a factor. Include a free-body diagram showing the forces at launch. Answer to the nearest whole unit in kN.
QUESTION 19 (9 marks) An empty cable car with a mass of 1500 kg is being lowered down a track on a 25° incline at a constant velocity of 2 m/s when the cable snaps releasing the cable car. The cable car`s emergency braking system engages when its velocity reaches 5 m/s and increases the coefficient of friction between the cable car and the track from 0.01 to 0.6 bringing it to a complete stop. A warning siren activates when the cable car is 10 metres from the original point of cable failure if it has not come to a stop. Determine the stopped position of the cable car relative to the warning siren`s activation point. Answer to the nearest whole unit in metres.
QUESTION 20 (6 marks) A pulley system moves a generator with a mass of 300 kg up a 15° incline. The coefficient of static friction between the incline and the generator is 0.3. This content has not been published for copyright reasons. Deteninine the tension in the pulley rope required at E to almost begin moving the generator up the incline if the pulley system is 80% efficient. Answer to two decimal places. Assume that the pulley system is parallel to the incline.
QUESTION 22 (9 marks) An airport luggage handling system consists of three connected sections. » Section 1: Luggage slides away from the aircraft down a 25-metre-long steel ramp set at 45° to the horizontal. » Section 2: Luggage travels along a 45-meire-long motorised horizontal conveyor. » Section 3: Luggage travels along a 30-metre-long motorised variable-speed horizontal conveyor before reaching the luggage carousel. This content has not been published for copyright reasons. Determine the revolutions per minute (rpm) of the variable-speed conveyor motor in Section 3 if the coefficient of kinetic friction (x;) between luggage and steel is 0.42 and the luggage * takes 20 seconds to move from the aircraft to the carousel * spends half as long in Section 2 as Section 3. Answer to the nearest whole unit. State any assumptions made.
QUESTION 1 The block in the figure above is raised on an inclined plane to an angle of 20°. The coefficient of static friction 1s 0.25. The statement that best describes the action of the block is that it will (A) not move. (B) slide at a constant rate down the incline. (C) slide at a decelerating rate down the incline. (D) slide at an accelerating rate down the incline.
QUESTION 3 ) ) e J ‘ [~ Forward When the vintage machine in the figure above is moving forward the motion of rod connection A is best described as (A) reciprocal and linear. (B) rotary and reciprocal. (C) rotary and oscillating. (D) reciprocal and oscillating.
QUESTION 6 The gear train in the figure above is driven by gear C. Gear B is an idler gear. The velocity ratio of gear A to gear C 1s (A) 9:1 (B) 3:2 C©) 1:2 (D) 2:3
QUESTION 8 A 1000 kg carriage 1s moving unimpeded by wind or friction down a roller-coaster at an angle of 45°. The acceleration of the carriage on the roller-coaster is (A) 2.87 m/s` (B) 6.93 m/s` (C) 7.07 m/s` (D) 9.80 m/s`
QUESTION 11 (2 marks) Describe how one feature of a bicycle provides the rider with a mechanical advantage.
QUESTION 12 (3 marks) The wheelbarrow in the figure above is used by the operator to raise a 100 kg load of firewood from the ground. The weight of the load is located 500 mm from the wheel axle. Explain the relationship between the load and the effort required to raise the load. Use mathematical reasoning to support your explanation.
QUESTION 14 (6 marks) Recall an engineering problem that required machines or mechanisms as part of the engineered solution. Explain how the community involved benefited from the solution and describe the types of engineering knowledge and expertise that were used during solution development. Make reference to materials forces mechanisms and community impacts.
QUESTION 18 (4 marks) During construction of an apartment block a crane elevates a 500 kg payload to a vertical distance of 50 m in 59 seconds at a constant speed as represented above. a) Calculate the work done by the crane during the vertical lift. [2 marks] b) Determine the power generated by the crane. [2 marks]
QUESTION 19 (6 marks) The diagram above shows a 50 kg bearing block sitting motionless on the verge of sliding on an inclined plane. Determine the normal force between the bearing block and the inclined plane if the force opposing motion of the block down the incline is 245 N. Include a force diagram with your working.
QUESTION 20 (5 marks) An electric motor and winch are used to lift 500 kg of soil in a 150 kg steel hopper a distance of 5 m in 20 seconds with uniform velocity. The energy efficiency of the winch is 75%. Calculate the input power required to lift the soil in the steel hopper.
QUESTION 21 (4 marks) Calculate the effort required to lift a load of 1 tonne using the pulley system in the diagram above. The pulley system has an efficiency of 85%.
QUESTION 22 (8 marks) The car jack shown above has a single start thread of effective diameter 30 mm and a 6.5 mm pitch. A force is applied to the lever handle of the car jack at a point 350 mm from the axis of the thread to lift a 2.5 tonne car 100 mm in half a minute. The jack has an efficiency of 45%. Determine the power required to lift the car to the nearest whole unit.
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