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AUSTRALIAN MATRICULATIONSUNWAY UNIVERSITY COLLEGE

2015 2 PHYSICS

Question 1 (4 marks)

A 700.0 kg roller coaster car at the Royal Show starts 40.0 m above the ground, goes down a dip in the track and just manages to roll over the next hill which is 33.0 m above ground level.

a. Calculate the amount of energy the car has lost.(2marks)

b. Neglecting energy losses, what is the maximum height above the ground the roller coaster car can achieve as it negotiates successive hills and dips? Explain your answer. (2 marks)


A nut on a bolt on a bicycle requires a torque of 6 N m to just loosen it. Label the diagram below and calculate force (F) that would just supply enough torque to loosen the nut if the length (L) is 25 cm.


2015 3 PHYSICS


Draw diagrams to illustrate the magnetic fields near the following:


Bill and Jane get their car stuck in sand. They tie a non-stretch rope to the car and pull together with a force of 800N, but they are unable to move the car. Bill then notices a tree 12 metres behind the car. He ties the other end of the rope tightly around the tree trunk and then they pull the middle of the rope sideways a distance of 0.50 m with a force of 800N. What force does the rope now exert on the car?


2015 4 PHYSICS


A loop the loop toy is designed a shown below. A toy car of mass (m) can be placed at various heights above the ground and released. When released from a sufficient height it will travel round the loop without falling off the track. The radius of the track is (d) and acceleration due to gravity is (g). Write an expression using the above symbols for the minimum speed (v) the car must have at point (P) if it is to complete the loop without falling off.


Students construct a model electric heater in the laboratory using two lengths of nichrome wire as heating elements. The two wires have resistances of 10.0 and 20.0 respectively.If the two lengths of nichrome wire were connected in parallel with the 12 V battery, calculate the current that would flow through each wire and the total power produced.


2015 5 PHYSICS


The diagram below shows a single rectangular loop of wire free to rotate in an uniform magnetic field of 0.06 T. The loop is carrying a current of 2.50 A and is 8.0 cm long an 3.0cm wide. What is the maximum force which would be exerted on one of the longer sides as the loop rotates?


A person bends over and holds a 20 kg object as shown in the picture. Her back is horizontal. The back muscle is attached to a point half way along the upper body (which includes the head), and the angle between the spine and muscle is 12°. The shoulders are two thirds of the way along the upper body. Assume that the object is vertically below the shoulders. This is modelled in the schematic diagram on the right.

a. Show all the forces acting on the back on the schematic diagram above.

(4 marks)

b. Find the tension in the back muscle in the position shown. Take the length of the

upper body to be 1.00 m and its mass as 35 kg. (5 marks)


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c. The back muscle will be injured if a force greater than 3500N is applied. Find the

maximum mass that person can lift, without injury, in the manner shown in the

picture

(5 marks)


A helicopter is required to drop emergency equipment to a group of walkers stranded in rugged bushland. A package is released from the helicopter at altitude (h) directly above the group. The helicopter is moving with a velocity of 8 km h¯¹ at an angle of 40° above the horizontal when the package is released. The package lands on the ground 2.5 s after being released.

a. Calculate the value of h. (3 marks)

b. If the helicopter continues to fly with its initial velocity, calculate the distance between the helicopter and the package at the instant the package hits the ground.

(2 marks)


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c. On the axes below draw a graph that best represents the vertical speed of the package as a function of time. Include actual values on the axes. Show calculations that determine significant points on the graph.

(3 marks)

If you wish to have a second attempt at this item, the graph is repeated at the end of the examination booklet on page 45. Indicate clearly on this page if you have used the second graph and cancel the working on the graph on this page.


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d. If the helicopter was travelling horizontally at the same speed (8 km h-1) and height (h) when it released the package, would you expect the package to land closer or further away from the group? Explain your answer.

(3 marks)


A satellite provides information about the receding glaciers on the Earth’s surface. It has a mass of 395 kg and is in a circular orbit of radius 1.45 x 104 km. By orbiting for 12 days it can map most of the Earth’s glaciers.

a. Calculate the orbital speed of the satellite.(3marks)

b. At what altitude above the Earth is the satellite orbiting?(3marks)

c. List the force(s) that keep the satellite in its stable circular orbit.(2marks)

d. On the diagram below draw one or more labelled arrows to show the direction of the force(s) on the satellite as it orbits the Earth.

(2marks)


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e. Would you expect this satellite to be in a geostationary orbit about the Earth? Explain your answer.

(2 marks)


2015 10 PHYSICS


Four identical light globes, G1, G2, G3 and G4 are connected in a circuit as shown below. The DC supply voltage is 24V and ammeter A3 connected to the circuit reads 0.096A

a. Calculate the current in each of the ammeters A1, A2 and A4. (3 marks)

b. Calculate the resistance of each light globe. (3 marks)


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c. Which light globe will be the brightest? Justify your answer. (2 marks)

d. Calculate the total power consumed by all four light globes. If you were unable to determine the answer in part (a) you should assume the current in ammeter A4 is 0.300A. (2marks)

e. If globe G3 is broken, describe how the brightness of each of the light globes G1 and G2 changes. Give a reason in each case. (4 marks)

The brightness of G1 will ______________________________________because _____________________________________________________________________________________________________________________________________________________________________________

The brightness of G2 will _______________________________________because _____________________________________________________________________________________________________________________________________________________________________________


2015 12 PHYSICS


In a DC motor (see figure below), the coil consists of rectangular loops of wire mounted on an axle rotating in a magnetic field of 0.45 T. The current in the wire is 5.6 A.

a. What force acts on each centimetre length of the wire? (4

marks)

b. The coil is made up of 420 loops, each 225mm long and 120mm wide. The axle is mounted parallel to the long axis of the loops. Calculate the maximum torque produced by this motor. (4 marks)


2015 13 PHYSICS

c. Figure 8 below shows a coil with several turns at varying stages in its rotation. The coil is viewed along the axle of the motor (line XY in the figure above). In each diagram, the symbols are as follows:

The axle (or axis of rotation is a shaded circle).

A wire carrying current into the page is shown as

A wire carrying current out of the page is shown as A line of magnetic flux is shown as

State clearly which of the diagrams show (or shows the coil when its torque is a maximum, and which of the diagram show (or shows the coil when its torque is a minimum. (4 marks)


2015 14 PHYSICS


Playing a hard game of tennis, Pat Strafer hits a ball at an angle of 1.5° above the horizontal at a speed of 55 ms-1. At the instant he hits it, the ball is 0.35 m above the ground.

a. Sketch the trajectory (path) of the ball from the racquet to the ground, without air resistance. [2 marks]

b. On the same sketch, show how air resistance will affect this trajectory. Label your sketch clearly. Explain why air resistance has this effect. [4 marks]

c. Is there any time at which the ball will have a zero acceleration between the time it is hit and the time it reaches the ground? Give a reason for your answer.

[3 marks]


2015 15 PHYSICS

For the following parts, ignore air resistance.

d. Find the time the ball is in the air from the moment it is hit to the time it reaches the ground. [4 marks]

e. Find the horizontal distance travelled in this time. If you were unable to get an answer for part (d) above, you may use the value 0.5 s as the time of flight.

[3 marks]


2015 16 PHYSICS


2015 17 PHYSICS


Poles that support electricity wires often have a cable running at an angle down to a support buried in the ground. The purpose of these cables is to stop the electricity wires from pulling the poles over. The diagram below shows one such pole.

a. With the aid of a diagram, explain how the cable helps prevent the pole being pulled over by the electricity wire [4 marks]

b. Suppose that the force exerted by the electricity wires on the on the pole shown in the diagram is 1500 N. Calculate the tension in the support cable so that the pole is not moved in any direction. Assume the wires make an angle of 87° with the pole.

[6 marks]


2015 18 PHYSICS

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Documents

marks question

marks bill

marks students

marks draw diagrams

toy car of mass

roller coaster car

loop toy

maximum force