A calculate the time taken for the fish to reach the

a) Calculate the time taken for the fish to reach the water.
5.20 m s -1
36.6°
This diagram is
NOT to scale
14.7 m
(4)
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Year 12 Physics 2011 Stage 3 13
b) Calculate the horizontal distance that the fish travels during its flight back to water.
(3)
c) Calculate the maximum height above the water that the fish reaches during its flight.
d) Sketch the altered flight path onto the diagram.
e) Will the time of flight be longer or shorter when air resistance is taken into account? Discuss
the factors that affect this.
(2)
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Year 12 Physics 2011 Stage 3 14
Question 16 (12 marks)
A mining company use an electric pump with an operating voltage in the range 1.25 kV-1.50 kV.
There is only a 240 V
RMS
supply available. A transformer is used to step up the output voltage to
1.50 kV
RMS
. The secondary winding of the transformer has 2000 turns of wire.
a) Calculate the number of turns required on the primary winding of the transformer.
(2)
240 V 1.50 kV
Electric Lift (Vd = 1.45 kV)
Cables
Transformer
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b) Calculate the total resistance of the cables. (4)
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Year 12 Physics 2011 Stage 3 15
c) Calculate how much electrical energy per second is transformed to heat in the cables.
(2)
d) Describe two design features of a commercial transformer that increase its efficiency.
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e) Explain why it is more efficient to transfer electricity to the pump at a high voltage of 1.50 kV
rather than 240 V.
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