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HSC Physics Marathon 2013-2015 Archive (1 Viewer)

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Crisium

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re: HSC Physics Marathon Archive

Fizzy can you post a few curveball questions for space and motors and generators up?

Meanwhile:

Why do some planets have no atmosphere? <-- Answer must be related to space module
 

Drsoccerball

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re: HSC Physics Marathon Archive

Fizzy can you post a few curveball questions for space and motors and generators up?

Meanwhile:

Why do some planets have no atmosphere? <-- Answer must be related to space module
Every planet has an atmosphere as you can never have a complete vacuum...?
 

Fizzy_Cyst

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re: HSC Physics Marathon Archive

Compare the EMF induced in a simple DC motor and an AC induction motor (5 marks)
 

Rhinoz8142

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re: HSC Physics Marathon Archive

^ pretty easy..just think about the structure of both
 

PhysicsMaths

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re: HSC Physics Marathon Archive

For DC motors, a changing flux caused by relative motion between an external magnetic field and the motor coils will induce an EMF induces a current that creates a magnetic field to oppose the change that caused it in the first place. In contrast, a changing flux for A.C. induction motors will induce an EMF that creates a current to support the motion of the rotor (torque created by the induced current is in the same direction as the "rotating" magnetic field).
For DC motors, the induced EMF will effectively travel in a single direction (due to S.R.Cs). For A.C induction motors, multiple sets of opposing stator coils (usually 3 phase) will induce EMF in an alternating direction.
The induced EMF in D.C. motors is caused by the rotation of the rotor coils through an external magnetic field. For A.C. induction motors, the induced current is caused by the "alternating" magnetic field of the stator.
 

astroman

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re: HSC Physics Marathon Archive

any know this, a car is parked on a slope, the coefficient of friction between the tyres and surface is 0.25, at what angle will the car slide?
 

keepLooking

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re: HSC Physics Marathon Archive

any know this, a car is parked on a slope, the coefficient of friction between the tyres and surface is 0.25, at what angle will the car slide?
tan-1(0.25) = 14.04
 

astroman

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re: HSC Physics Marathon Archive

Not really a question but what would be the best diagram to draw for explaining the relativity of simultaneity in an exam?
 

astroman

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re: HSC Physics Marathon Archive

using that i get an answer for the question as 15.6g, it doesn't seem reasonable for an astronaut during lift off.
 
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