HSC Physics Question Thread

[jamonwindeyer]

im having trouble visualising this... pls help!

the star ship enterprise Enterprise is stationary in space to make repairs to the warp
drive. Suddenly a Kinglon vessel appears from the right and flashes towards and past the Enterprise at half the speed
of light.
When it is exactly in front of the Enterprise, Captain Kirk fires port and starboard at the same time.

so this is how i interpreted it... (too lazy to upload a pic)

i have Enterprise stationary (on a planet) with Kinglon whizzing past going left...
and then i get lost with where the lasers are going...

This is majorly confusing; I don't blame you for being lost

I'm with Rathin's interpretation. To simplify it, here is (I think) the exact same scenario without all the Star Trek references:

A train travelling at half the speed of light races past a platform, from right to left. The train is the same length as the platform. When the train and platform are directly aligned, fireworks are let off at either end of the platform.

Here, the ships are replaced with a platform and train, and the lasers with fireworks. It is just a weird version of Einstein's thought experiment, I think

[Aaron12038488]

Discuss problems produced by the limited range of the electromagnetic spectrum available for communication purposes.
How do I go about in this dot point.

[jamonwindeyer]

Discuss problems produced by the limited range of the electromagnetic spectrum available for communication purposes.
How do I go about in this dot point.

Basically your points here will concern the fact that we only have a limited number of channels. Because we can only use a certain range of the EM spectrum safely, that limits how many frequencies we can use to communicate.

Practically, this causes a congestion of frequencies. We need to allocate frequencies to certain purposes and ensure no one overlaps; without these precautions, you'd get interference everywhere. For example, FM radio stations get frequencies somewhere near 80-110 MHz in Australia (with some research you could probably get the actual allocations), these are the only ones they can use.


Really, you can summarise this in your notes as just congestion of frequencies, I didn't have much more than that

[Aaron12038488]

Thanks, one other question,
Describe ways in which applications of reflection of light, radio waves and microwaves have assisted information transfer.
For this dot point, do we have to talk about each one, or just in general

[jamonwindeyer]

Thanks, one other question,
Describe ways in which applications of reflection of light, radio waves and microwaves have assisted information transfer.
For this dot point, do we have to talk about each one, or just in general

Each one; they are all slightly different (light is especially different to radio/micro waves)

[Rathin]

Discuss problems produced by the limited range of the electromagnetic spectrum available for communication purposes.
How do I go about in this dot point.

The main reason of the limiting the range assigned for communication is that the government is attempting to avoid interference with other radio signals such as the emergency services. This creates problems as it limits the bandwidth allocated for communication from 500 kHz to 300 GHz which then creates a congestion of frequencies.

To minimise these problem scientists are researching the possibility of using the frequencies near Infrared waves to increase the number of users.

The use of cables also increases the number of users as it allows far greater volume of communications as cable networks have no bandwidth limitations and extra cables can be installed.

[Rathin]

Thanks, one other question,
Describe ways in which applications of reflection of light, radio waves and microwaves have assisted information transfer.
For this dot point, do we have to talk about each one, or just in general

- Reflection of light is used in optic fibres which allows massive amounts of information transfer.
- Radio waves reflects off the ionosphere which allows the information to be transferred long distances.
- Microwaves are used in radars which reflect off objects to determine the distance of that object.

[jamonwindeyer]

For light, you can also include mirrors in things like telescopes and camera lenses!

[Aaron12038488]

Just out of curiosity,
How much maths is involved in Preliminary and HSC Physics?

[RuiAce]

Just out of curiosity,
How much maths is involved in Preliminary and HSC Physics?

About the same difficulty as general maths.

Quantity wise, there's probably a 30%-70% split between maths and theory, or something like that

[jamonwindeyer]

Just out of curiosity,
How much maths is involved in Preliminary and HSC Physics?

There is probably a bit more in Prelim, because you'll deal with vectors, which involves a fair bit of trigonometry!

As long as you can rearrange equations, do some basic right-angled trigonometry (and perhaps a few other little bits and pieces, a bit of geometry) you'll be totally sweet

[jakesilove]

Just out of curiosity,
How much maths is involved in Preliminary and HSC Physics?

Basically, if you can sub numbers into equations, and do some algabraic rearranging, you'll be fine I know plenty of people who weren't very confident with mathematics, but after enough practice could smash out Physics maths questions with ease! Whether you're brilliant at Maths, or shudder at the thought of it, with enough practice you'll be fine

[Rathin]

Surprisingly the knowledge in Vectors in prelim physics helped me in complex vectors!

[jamonwindeyer]

Surprisingly the knowledge in Vectors in prelim physics helped me in complex vectors!

Yeah ditto!! The new syllabus has 3 dimensional vectors being used, so in a few years it will be even more useful

[RuiAce]

Surprisingly the knowledge in Vectors in prelim physics helped me in complex vectors!

In my MX2 class, there were only 3 students including me. 2 of which did physics.

The guy who didn't do physics was the one having difficulty at the start with vectors.

Yeah ditto!! The new syllabus has 3 dimensional vectors being used, so in a few years it will be even more useful

I hope they use the matrix notation though and not the dumb i j k stuff...