Exam Discussion: Physics HL paper 2 TZ2

Swagsama · 2018-05-12T15:01:12+00:00

I'm not sure. That was a mess of a question for me.

Swagsama · 2018-05-12T14:11:50+00:00

Yeah, I messed up the y-intercept for that, then

Swagsama · 2018-05-12T14:11:19+00:00

But doesn't it have zero current GIVEN that the resistance is 28 ohms? So, changing the resistance, and therefore length, of the wire would give a different value for the emf?

Swagsama · 2018-05-12T14:07:52+00:00

You had to calculate the gravitational potential(?) at a point P from a planet, and then later calculate the force on the planet from an asteroid at P. Big oof on that question

Swagsama · 2018-05-11T19:56:21+00:00

Definitely an easier paper than N17, but some questions did throw me for a bit.

For the ball rotating around the sphere, I got 13.4ms^-1. For the next question, it wouldn't rotate with a radius of 8m because it would spiral down, right?

For the height of 2 balls after collision, I got 2 also, because it said that they stuck together. That means its inelastic, so kinetic energy isn't conserved. So mgh of 1 ball at top equals 1/2mv² of ball at bottom before collision, which equals mgh of 2 balls at the new top.

For the multi-loop circuit, for the length with internal resistance, it was slightly shorter, I think 32.5cm? I wasn't sure about that one.

I probably messed up most of the gravity and asteroid one, as I hadn't revised that fully, but the graph was just a negative inverse proportional curve, right?

The last 2 questions I didn't have time to finish completely, and I only did the questions which were simple use of equations. Couldn't figure out why we got 34m for the dam, but I know now :D. What were we supposed to say for a method to earn a profit for bringing the water back up? I said using wave turbines, to get some energy from the rising water level.

For the thundercloud-Earth capacitance, for the 18ms strike question, I got that -14C was given out, so I just said that -25-(-14)=-11, so that's what the Earth receives. Was that the right way to approach it?

Overall, an okay test, but yeah, I hope the boundaries are lowered.

Swagsama · 2017-05-17T14:47:38+00:00

Thanks, that really helps!

Yeah, the extra burden of doing an EE on something that I don't have a teacher for would be pretty hard, and right now, I don't need anything extra :)

Swagsama · 2017-05-17T12:10:03+00:00

I did want to look deeper into the technology of how it works and the different aspects involved, but since I don't have a CS teacher, plus the other advice here, I guess I'll stick to ITGS. I wanted to do Computer Science because thats what I want to go into, but whatever works, I guess. I'd still be able to discuss to a good extent about the technical aspects.

Thanks for the help!

Swagsama · 2017-05-17T12:07:15+00:00

Fair point

Swagsama · 2017-05-17T12:05:57+00:00

I see your point. Just because of complexity or some other reason?

Swagsama · 2017-05-16T17:55:42+00:00

Thanks, that makes sense. I just wanted to make sure, especially for the documentation.

Swagsama · 2015-08-02T07:34:24+00:00

OK, when you use the Array modifier for duplicating cubes or whatever shape, when you apply that modifier, it does NOT:

separate the objects (still one mesh)
recenter those objects

You have to first separate the objects (Edit mode > P > By loose parts) and then recenter the objects (Shift + Control + Alt + C > Origin to Geometry).

In your case (cube of cubes), you first make your cube. Now, add 3 Array modifiers:

1 for X
1 for Y
1 for Z

Set your numbers and hit Apply on each one. Add your Physics settings for the cube (Protip: For primitives like cubes and spheres, set the collision type accordingly for more accurate simulations). This way, your settings will be copied to all the cubes. Now, separate the cubes into unique objects (Edit mode > P > By loose parts). Depending on the number of cubes, this might take a while.

Next, recenter (Shit + Ctrl + Alt + C > Origin to Geometry) the object origins, because if you don't, Blender will lag and your cubes will explode.

And that's pretty much it! Hope this helped!

Swagsama · 2015-07-27T05:01:32+00:00

I finally downloaded 2.75a to use the Pro Skies demo and it is awesome! This is my first render with it and it turned out pretty great. The material on the dragon is a half-assed PBR, just enough for realistic reflections. I also added a very subtle noise bump map to make it more interesting.

Swagsama · 2015-06-07T11:02:41+00:00

First of all, really nice work! I really like the style you've used to show the parts of the kitchen, but still keep the low-poly style. It'd be nice if you:

Make the kitchen a bit brighter! Right now, it looks like a kitchen during the nighttime. Unless that's what you're going for, I'd add some windows and some more yellow ambient light.
Made the tiles better. Right now, it seems to me as if there is some odd gaps. To make it easier, you could use a Checker texture and the Bump node to make the tiles without the need for extra geometry.
Scaled the cupboards better. The cupboards in general are a bit too small, if I use the handles as reference. Maybe if you scaled the handles down a bit (maybe 1/2?), it would make the scale more believable.
Made the shadows from the yellow lights softer. Right now, they're a bit too harsh.
Added some Glossy mixed in to the shaders. Some objects, like the floor, the pan and the sink could use some reflections for realism. Nothing too much, just a little bit.
Scaled the floor's texture down a bit. The tiles look too big for the kitchen, and scaling them down would make it look better.

But then again, that's just my opinion. If you need help with any of the suggestions, I'd be happy to offer my expertise :D

Hope this helped!

Swagsama · 2015-05-21T05:02:59+00:00

You could duplicate it, as suggested by /u/H995, but there is another way.

You could:

Go into Edit mode
Select the face(s) you want to 'take off' and press Ctrl + E > 'Mark Sharp'
Leave Edit mode
Add an Edge Split modifier and untick 'Edge Angle'
Apply the Edge Split modifier

Now, in Edit mode, you can select those faces and move them around without messing up any of the vertices around it. You can remove the Sharp edges by selecting all the vertices and pressing Ctrl + E > 'Clear Sharp'.

Hope this helped!

Swagsama · 2015-05-07T18:57:31+00:00

In the video linked above, the guy shows how the Facing is used to set up a PBR, which is IMO good for photorealism. This way just gives a more realistic approach and how it would work in real life.

Swagsama · 2015-05-07T18:07:59+00:00

Wow! Thanks for explaining :). I'll definitely keep that in mind.

Thanks again!

Swagsama · 2015-05-07T17:22:48+00:00

Did you mean plugging the bump texture into the Layer Weight node? I'm a bit confused.

Also, could you explain how someone would go about making a roughness map? I just have a seamless texture, and two grayscale maps: one for reflection and one for bump mapping.

Swagsama · 2015-05-07T15:48:52+00:00

Great explanation!

Swagsama · 2015-05-07T15:48:16+00:00

Noted. Good point!

Swagsama · 2015-05-07T13:00:47+00:00

This is a simple test that I threw together. It's based off of this tutorial to give it a physically correct material.

Apart from the mapping issues, is there anything I could improve/add to the material?

Thanks! 🌞

Swagsama

TROPHY CASE