• Log InLog In
  • Register
Liquid`
Team Liquid Liquipedia
EDT 11:14
CEST 17:14
KST 00:14
  • Home
  • Forum
  • Calendar
  • Streams
  • Liquipedia
  • Features
  • Store
  • EPT
  • TL+
  • StarCraft 2
  • Brood War
  • Smash
  • Heroes
  • Counter-Strike
  • Overwatch
  • Liquibet
  • Fantasy StarCraft
  • TLPD
  • StarCraft 2
  • Brood War
  • Blogs
Forum Sidebar
Events/Features
News
Featured News
Power Rank - Esports World Cup 202559RSL Season 1 - Final Week9[ASL19] Finals Recap: Standing Tall15HomeStory Cup 27 - Info & Preview18Classic wins Code S Season 2 (2025)16
Community News
BSL Team Wars - Bonyth, Dewalt, Hawk & Sziky teams10Weekly Cups (July 14-20): Final Check-up0Esports World Cup 2025 - Brackets Revealed19Weekly Cups (July 7-13): Classic continues to roll8Team TLMC #5 - Submission re-extension4
StarCraft 2
General
The GOAT ranking of GOAT rankings Power Rank - Esports World Cup 2025 What tournaments are world championships? RSL Revival patreon money discussion thread Jim claims he and Firefly were involved in match-fixing
Tourneys
Esports World Cup 2025 Sparkling Tuna Cup - Weekly Open Tournament FEL Cracov 2025 (July 27) - $8000 live event Master Swan Open (Global Bronze-Master 2) Sea Duckling Open (Global, Bronze-Diamond)
Strategy
How did i lose this ZvP, whats the proper response
Custom Maps
External Content
Mutation #239 Bad Weather Mutation # 483 Kill Bot Wars Mutation # 482 Wheel of Misfortune Mutation # 481 Fear and Lava
Brood War
General
BW General Discussion Dewalt's Show Matches in China [Update] ShieldBattery: 2025 Redesign Ginuda's JaeDong Interview Series BSL Team Wars - Bonyth, Dewalt, Hawk & Sziky teams
Tourneys
[Megathread] Daily Proleagues CSL Xiamen International Invitational [CSLPRO] It's CSLAN Season! - Last Chance [BSL 2v2] ProLeague Season 3 - Friday 21:00 CET
Strategy
Does 1 second matter in StarCraft? [G] Mineral Boosting Simple Questions, Simple Answers
Other Games
General Games
Stormgate/Frost Giant Megathread Nintendo Switch Thread [MMORPG] Tree of Savior (Successor of Ragnarok) Path of Exile CCLP - Command & Conquer League Project
Dota 2
Official 'what is Dota anymore' discussion
League of Legends
Heroes of the Storm
Simple Questions, Simple Answers Heroes of the Storm 2.0
Hearthstone
Heroes of StarCraft mini-set
TL Mafia
TL Mafia Community Thread Vanilla Mini Mafia
Community
General
Russo-Ukrainian War Thread US Politics Mega-thread Things Aren’t Peaceful in Palestine Post Pic of your Favorite Food! The Games Industry And ATVI
Fan Clubs
SKT1 Classic Fan Club!
Media & Entertainment
[\m/] Heavy Metal Thread Anime Discussion Thread Movie Discussion! [Manga] One Piece Korean Music Discussion
Sports
Formula 1 Discussion 2024 - 2025 Football Thread TeamLiquid Health and Fitness Initiative For 2023 NBA General Discussion
World Cup 2022
Tech Support
Installation of Windows 10 suck at "just a moment" Computer Build, Upgrade & Buying Resource Thread
TL Community
The Automated Ban List
Blogs
Ping To Win? Pings And Their…
TrAiDoS
momentary artworks from des…
tankgirl
from making sc maps to makin…
Husyelt
StarCraft improvement
iopq
Socialism Anyone?
GreenHorizons
Eight Anniversary as a TL…
Mizenhauer
Customize Sidebar...

Website Feedback

Closed Threads



Active: 840 users

Study Blog Part 3: Center of mass

Blogs > Mr.X546
Post a Reply
Zhazulo
Profile Blog Joined February 2011
Sweden226 Posts
February 03 2013 20:27 GMT
#1
Hey all!

This week will be a rather short blog. I've had plenty to do (trying out new study habits, playing SC2, and else) but I wrote together a bit of the week!

Code S has really occupied me daily, hehe. With it being on at 10:10 AM more or less every day and our school having WiFi in every building, it's a bit too easy to tune in ^^ oh well!

I'll be playing at UniSL FInals next week. You know, the guys who made the "Land of the Zerg" video. I believe I'll be playing first on Saturday at 1 pm. Be sure to tune in then!

1) What have you done this week?

+ Show Spoiler +
i) Topics covered

Center of mass

ii) Time spent/what sessions?

Theory reading (1 x 2h)

4 calculation sessions (4 x 2h)

Repetition (~2 h)

Total=12 h

iii) Topics explained

I was supposed to go through free body diagrams in 2D as well, but there was a lot to do with just center of mass, so I ended up doing only that. Luckily, next week is only about FBDs and I managed to read the theory about FBDs in 2D, so I think it will be ok in the end.

Center of mass is about calculating the center of mass of an object or several objects. This is relevant because mechanics is about simplifying complex situations, and in many cases, objects can be approximated by being a single point object, which would be located at it's center of mass.

Calculations include two areas; finding the center of mass of a system of particles or the center of mass for a body. In this case, we approximate the body to be a rigid body; it will NOT change form (more about that later on!)

Finding the center of mass of a particle system can be done with a straightforward formula; finding the sum of the particles' position vectors, multiplied by their corresponding mass, and then dividing the sum with the total amount of mass of the system.

A more common situation is to find the center of mass of a body. It get's a little trickier, but there are several techniques. Basically, the same principle applies; approximate the body to a particle. If the body is complex, the idea is to divide it into sub-bodies, calculate their center and then add them all up as a particle system.

To find the center of mass of a body (or a sub-body!) we can use Pappus Rule. Pappus rule relates the area or volume of rotation around an axis to the center of mass and the line or area which is to be rotated. The equations are as following:

Volume of rotation=2(pi)*Yg*Area
Area of rotation=2(pi)*Yg*Length

where:
Yg - is the y-coordinate of the center of mass (if the figure is to be rotated around the x-axis)

Most of this theory will become understandable when it comes to solving problems, that's when the learning really happens!

iv) What challenges did you face?
Most of the exercises were tedious and quite daunting to start at, but it got easier and easier the more comfortable I got! The main focal point was just to do calculations


2) Problems/Exercises

+ Show Spoiler +
No exercises this week either maybe I'll have to rethink how I should approach this section, as I have yet to upload a single exercise ^^


3) Reflection Questions
+ Show Spoiler +
How would Pappus Rule be applied if the rotation would only be half-way?

How can Pappus Rule be used to find the area and/or the volume of a figure?


4) For Next week
+ Show Spoiler +
i) What topics? What do you know about this?
Next week will be about free body diagrams, but I discussed this last week, so nothing really new to add here!


Have a week!

ThePhan2m
Profile Blog Joined September 2004
Norway2750 Posts
Last Edited: 2013-02-03 21:58:04
February 03 2013 21:57 GMT
#2
Good job, expecting some exercise pictures next week!!
RoyGBiv_13
Profile Blog Joined August 2010
United States1275 Posts
February 04 2013 18:32 GMT
#3
Sort of related to your blog:

A homework short story:
+ Show Spoiler +
As a freshman at engineering college, I had fast-tracked my way into taking multi-dimensional calculus through AP classes in high school. The calculus professor, Dr. Alden, used the Mathematica-like program, Maple, nearly every day to show us examples of how to do incredibly complicated equations using the school-issued (and tuition bloating) laptops. The brightest students quickly caught on that you could use this program to do your homework. You could just print out the results instead of breaking your wrist writing page after page of equations that you inevitably just plugged into the computer anyway.

There was an extensive library as part of Maple. It could do all sorts of animations, differential equations, symbolic logic and really anything a mathematician or engineer could need. There was even keyboard shortcuts to quickly format the worksheet to make it organized and able to be submitted for homework. Part of the skill in using the program was to learn how to ask questions of it. The help file was accessed by a quick "?<command>".

There was one notorious week, two weeks before the final, where Dr Alden had to teach several topics per day to accommodate the schedule. He would teach one subject during the lecture, then assign another for homework. Naturally, calculating the center of mass was a homework assignment. One not even covered in the textbook. The entire class was confused over the instructions and examples (the topic itself isn't too difficult, but there are a number of tricky things in multivariable land that quickly catch up with you). Only three of us turned in the homework on time.

It was my shortest homework assignment since elementary school. It took me under 3 minutes to complete.

The trick? "?Centerofmass".... Turned out that Maple had a CenterOfMass(f(x,y,z),x=A..B,y=C..D,z=E..F) command. I transcribed the functions into the program, ran the worksheet, and printed it. The average length of that homework (the prof recorded these stats, being a Math prof and all) was 11 pages. He had exclude my 100% homework of 2 pages as an outlier.

Any sufficiently advanced technology is indistinguishable from magic
Please log in or register to reply.
Live Events Refresh
OSC
14:00
King of the Hill #219
davetesta19
Liquipedia
Esports World Cup
11:00
2025 - Final Day
Cure vs SolarLIVE!
Serral vs Classic
EWC_Arena16939
ComeBackTV 3523
TaKeTV 846
Hui .700
JimRising 560
3DClanTV 362
EnkiAlexander 261
Rex247
Fuzer 235
CranKy Ducklings122
Reynor121
SpeCial70
LiquipediaDiscussion
[ Submit Event ]
Live Streams
Refresh
StarCraft 2
EWC_Arena16939
Hui .700
JimRising 560
Rex 247
Fuzer 235
Reynor 121
UpATreeSC 113
SpeCial 70
StarCraft: Brood War
Bisu 4401
Horang2 3208
Shuttle 2908
EffOrt 1256
Larva 982
Mini 851
BeSt 641
Barracks 503
Stork 424
actioN 363
[ Show more ]
Soma 327
ggaemo 233
Soulkey 144
JYJ129
Snow 123
Hyun 117
Rush 115
TY 113
Sharp 55
sSak 38
Aegong 32
sorry 31
Sacsri 13
soO 13
JulyZerg 9
Bale 3
Dota 2
Gorgc7090
420jenkins349
XaKoH 303
syndereN302
XcaliburYe239
KheZu98
Counter-Strike
fl0m3244
sgares351
shoxiejesuss72
Other Games
gofns7278
singsing1952
ScreaM1594
Beastyqt793
FrodaN276
KnowMe151
ArmadaUGS123
QueenE81
Organizations
StarCraft 2
Blizzard YouTube
StarCraft: Brood War
BSLTrovo
sctven
[ Show 16 non-featured ]
StarCraft 2
• LaughNgamezSOOP
• AfreecaTV YouTube
• sooper7s
• intothetv
• Migwel
• Kozan
• IndyKCrew
StarCraft: Brood War
• blackmanpl 16
• Michael_bg 3
• STPLYoutube
• ZZZeroYoutube
• FirePhoenix0
• BSLYoutube
Dota 2
• WagamamaTV563
League of Legends
• Nemesis5935
Other Games
• Shiphtur171
Upcoming Events
CranKy Ducklings
18h 46m
BSL20 Non-Korean Champi…
22h 46m
CSO Cup
1d
BSL20 Non-Korean Champi…
1d 2h
Bonyth vs Sziky
Dewalt vs Hawk
Hawk vs QiaoGege
Sziky vs Dewalt
Mihu vs Bonyth
Zhanhun vs QiaoGege
QiaoGege vs Fengzi
FEL
1d 17h
BSL20 Non-Korean Champi…
1d 22h
BSL20 Non-Korean Champi…
2 days
Bonyth vs Zhanhun
Dewalt vs Mihu
Hawk vs Sziky
Sziky vs QiaoGege
Mihu vs Hawk
Zhanhun vs Dewalt
Fengzi vs Bonyth
Sparkling Tuna Cup
3 days
Online Event
4 days
uThermal 2v2 Circuit
5 days
[ Show More ]
The PondCast
5 days
Replay Cast
6 days
Liquipedia Results

Completed

CSL Xiamen Invitational
Championship of Russia 2025
Murky Cup #2

Ongoing

Copa Latinoamericana 4
Jiahua Invitational
BSL20 Non-Korean Championship
Esports World Cup 2025
CC Div. A S7
Underdog Cup #2
IEM Cologne 2025
FISSURE Playground #1
BLAST.tv Austin Major 2025
ESL Impact League Season 7
IEM Dallas 2025
PGL Astana 2025
Asian Champions League '25

Upcoming

CSLPRO Last Chance 2025
ASL Season 20: Qualifier #1
ASL Season 20: Qualifier #2
ASL Season 20
CSLPRO Chat StarLAN 3
BSL Season 21
RSL Revival: Season 2
Maestros of the Game
SEL Season 2 Championship
uThermal 2v2 Main Event
FEL Cracov 2025
HCC Europe
ESL Pro League S22
StarSeries Fall 2025
FISSURE Playground #2
BLAST Open Fall 2025
BLAST Open Fall Qual
Esports World Cup 2025
BLAST Bounty Fall 2025
BLAST Bounty Fall Qual
TLPD

1. ByuN
2. TY
3. Dark
4. Solar
5. Stats
6. Nerchio
7. sOs
8. soO
9. INnoVation
10. Elazer
1. Rain
2. Flash
3. EffOrt
4. Last
5. Bisu
6. Soulkey
7. Mini
8. Sharp
Sidebar Settings...

Advertising | Privacy Policy | Terms Of Use | Contact Us

Original banner artwork: Jim Warren
The contents of this webpage are copyright © 2025 TLnet. All Rights Reserved.