HSC Physics Question Thread

[jamonwindeyer]

For the syllabus point, "Describe the main features of an AC electric motor".
It says that we need one AC electric motor design so, can I use the motor which is highly similar to the DC motor or do I also have to do the AC induction motor?

^ To add to above, if you are doing your notes induction motors do have their own dot point later in the course!! When I did mine I just put a few quick notes on universal and 'basic' AC motors

[itssona]

any help pls? (quick if u can since exam soon)

[kiwiberry]

any help pls? (quick if u can since exam soon)

On the moon, W=224 and g=1.6. Using W=mg, we can find the astronaut’s mass to be 140kg. Using W=mg again with m=140 and g=3.72 instead, we can calculate their weight on Mars to be 520.8N

[Fizzycyst]

On the moon, W=224 and g=1.6. Using W=mg, we can find the astronaut’s mass to be 140kg. Using W=mg again with m=140 and g=3.72 instead, we can calculate their weight on Mars to be 520.8N

Careful! The question says mass. So it will be 140kg

[kiwiberry]

Careful! The question says mass. So it will be 140kg

Yes!!! Sorry, my bad!

[sadfd45678]

Hi guys,
When a satellite is orbiting, it is constantly falling under gravity. So why wouldn't it acceleration be 9.8 or whatever it is after it is re-arranged due to radius the satellite is orbiting at, rather than a=v^2/r?

Thanks

[jamonwindeyer]

Hi guys,
When a satellite is orbiting, it is constantly falling under gravity. So why wouldn't it acceleration be 9.8 or whatever it is after it is re-arranged due to radius the satellite is orbiting at, rather than a=v^2/r?

Thanks

Hey! So the \(g\) you mean in the first bit is from Newton's Law right?



But in an orbit, gravity provides a centripetal acceleration:





Essentially, you are right - It is 9.8 (or a slightly lower value anyway, based on altitude). And it is also \(\frac{v^2}{r}\). The two are the same, and when you put them together you get a way to derive the formula for orbital velocity

[Dragomistress]

^ To add to above, if you are doing your notes induction motors do have their own dot point later in the course!! When I did mine I just put a few quick notes on universal and 'basic' AC motors

Just curious, what is the dot point for the induction motor?

[Fizzycyst]

Just curious, what is the dot point for the induction motor?

The induction motor doesn’t have a theory dot point as such, just the practical dot point where you need to perform a practical to demonstrate the principle behind it.
But, in order to show how it demonstrates the principle, you need to know how it works.
I have seen Questions worth up to 5 marks in HYE and trials basically asking you to explain how an AC induction motor works.

[jamonwindeyer]

Just curious, what is the dot point for the induction motor?

Yep as above, now that I've looked at the syllabus again it isn't actually that much later at all - It is literally directly beside the "features of AC motors" one just a structural thing, I preferred to stick my notes on induction motors with the notes for the prac, important to structure your notes how best makes sense to you though

[8Dadeedo]

Hey can I please get some help with the following?

Thank ya

[Fizzycyst]

Hey can I please get some help with the following?

Thank ya

This seems about right!

Don't judge my drawings 

[sadfd45678]

Hi Guys
How do i prepare for physics MCQ. No matter how much I do there is always a couple that stumps me like the HSC 2017 Q17. Like there's always something that you havent thought about. If anyone has anytips on how to do well at it, please let me know. Thanks

[Fizzycyst]

The only way to prepare for the curve ball questions is to UNDERSTAND physics.
Past papers are a good way to consolidate understanding and look for different types of questions, but undoubtedly, there will be questions which ask you to bend your knowledge a bit to an unfamiliar context — this is what High Band 5 / Band 6 students are able to do. See a scenario, think of how their existing knowledge applies to the new scenario and then apply it.

You can’t know everything beforehand, you need to be able to APPLY what you know to the unfamiliar scenarios. No textbook and/or teacher and/or tutor teaches every possible type of question for every possible dot point, even if they think they do.

Teachers equip you with the skills you need, but you need to be able to APPLY.

Engineers aren’t like “Bruvv, never learnt this exact scenario in my 5 yr degree, must be impossibru” Rather, they twist what they are familiar with to apply to the given scenario.

This is where you need to be to address some of the harder MCQ. There is no “trick”, there is no magic NZT-48 for this, just hard work.

Hi Guys
How do i prepare for physics MCQ. No matter how much I do there is always a couple that stumps me like the HSC 2017 Q17. Like there's always something that you havent thought about. If anyone has anytips on how to do well at it, please let me know. Thanks

[clovvy]

A motor is connected in series with an ammeter and a 12V power supply. The internal resistance of the motor is 1.5 Ohms. When the motor is running at full speed, the ammeter reads 3.0 A. Account for this.