Simple Machines B/Compound Machines C

RontgensWallaby
Member
Member
Posts: 58
Joined: April 14th, 2015, 5:00 pm
Division: C
State: GA
Location: Small Magellanic Cloud (my messages may be a couple of years late)

Re: Simple Machines B/Compound Machines C

Postby RontgensWallaby » April 19th, 2015, 12:14 pm

Does anyone know how to solve number 4 on the Captain's Tryouts test for Compound Machines? :?:
Yeah, I spent so much time trying to figure out that one (and I still don't know); I never understood tension beyond what I needed to solve Div B level problems.
I think some free body diagrams would help here.

EDIT: I believe it's solved like this:
for first mass, and then just do the same thing for the other masses.
Hmm, the key says something different.

As of right now, I am only able to solve for the acceleration of their masses given their tension and mass, and I'm not really sure if I'm right.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

jkang
Member
Member
Posts: 107
Joined: October 17th, 2014, 8:49 pm
Division: Grad
State: TX

Re: Simple Machines B/Compound Machines C

Postby jkang » April 19th, 2015, 7:18 pm

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
UT Austin '19
Liberal Arts and Science Academy '15

sciolyboy123
Member
Member
Posts: 128
Joined: April 17th, 2015, 8:40 am
Division: B
State: AL

Re: Simple Machines B/Compound Machines C

Postby sciolyboy123 » April 19th, 2015, 11:00 pm

Where did the test go?
2014-15 Season
(Hooch,Dodgen, Regionals, State, Nats)
Bio-Process Lab(3rd,5th,-,3rd,14th ;) )
Disease Detectives (1st,5th,1st,1st,10th 8-) )
Crave The Wave (2nd,-,-,-,-)
Experimental Design (-,1st, 4th,-,-)
Picture This (4th,6th, 1st, 4th,48th :oops: )
Simple Machines (1st,n/a, 1st, n/a)

User avatar
Unome
Moderator
Moderator
Posts: 4122
Joined: January 26th, 2014, 12:48 pm
Division: Grad
State: GA
Location: somewhere in the sciolyverse

Re: Simple Machines B/Compound Machines C

Postby Unome » April 20th, 2015, 4:24 am

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
I was never quite sure what dynamic calculations were; is it just anything not in static equilibrium?
Userpage
Chattahoochee High School Class of 2018
Georgia Tech Class of 2022

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

Scio5ever
Member
Member
Posts: 5
Joined: April 3rd, 2015, 7:36 pm

Re: Simple Machines B/Compound Machines C

Postby Scio5ever » April 20th, 2015, 8:42 am

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
I was never quite sure what dynamic calculations were; is it just anything not in static equilibrium?
Essentially, yes, anything that involves calculating forces and whatnot related to bodies in motion is not allowed. At least that's my interpretation of the rules.

User avatar
samlan16
Member
Member
Posts: 523
Joined: December 30th, 2013, 2:54 pm
Division: Grad
State: TN
Contact:

Re: Simple Machines B/Compound Machines C

Postby samlan16 » April 20th, 2015, 12:12 pm

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
I was never quite sure what dynamic calculations were; is it just anything not in static equilibrium?
Essentially, yes, anything that involves calculating forces and whatnot related to bodies in motion is not allowed. At least that's my interpretation of the rules.
Err, no. That's allowed. Those problems are called net force problems.
Remember, we are proud of every team that participated and you are all winners.

RontgensWallaby
Member
Member
Posts: 58
Joined: April 14th, 2015, 5:00 pm
Division: C
State: GA
Location: Small Magellanic Cloud (my messages may be a couple of years late)

Re: Simple Machines B/Compound Machines C

Postby RontgensWallaby » April 20th, 2015, 3:11 pm

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
I was never quite sure what dynamic calculations were; is it just anything not in static equilibrium?
I would think so; the opposite of dynamic calculations should be static calculations, which would be anything in equilibrium. However I find it hard to believe that some basic dynamic calculations won't be included, for example the acceleration of masses on a fixed pulley would be something I would expect to come across at Nationals.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

UTF-8 U+6211 U+662F
Exalted Member
Exalted Member
Posts: 1518
Joined: January 18th, 2015, 7:42 am
Division: C
State: PA

Re: Simple Machines B/Compound Machines C

Postby UTF-8 U+6211 U+662F » April 20th, 2015, 3:25 pm

"Prohibited topics include: dynamic calculations"
Idk why everyone's trying so hard on that problem when it's never going to come up at nationals or anything .__.
I was never quite sure what dynamic calculations were; is it just anything not in static equilibrium?
I would think so; the opposite of dynamic calculations should be static calculations, which would be anything in equilibrium. However I find it hard to believe that some basic dynamic calculations won't be included, for example the acceleration of masses on a fixed pulley would be something I would expect to come across at Nationals.
Of course, you can ask questions about forces... it's just that has to equal zero.

RontgensWallaby
Member
Member
Posts: 58
Joined: April 14th, 2015, 5:00 pm
Division: C
State: GA
Location: Small Magellanic Cloud (my messages may be a couple of years late)

Re: Simple Machines B/Compound Machines C

Postby RontgensWallaby » April 21st, 2015, 6:43 pm

http://img.sparknotes.com/content/testp ... pulley.gif
A problem I just came up with. Solved it and just want to make sure I'm right since I doubt my coach will know how to solve it (it's not that complicated).
In the diagram from the link, angle θ is 37 degrees and mass m is 15 kg. The coefficient of friction between mass m and the inclined plane is 0.4. Assume the pulley is frictionless. What are the maximum and minimum masses for mass M if the system is in equilibrium?
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

jkang
Member
Member
Posts: 107
Joined: October 17th, 2014, 8:49 pm
Division: Grad
State: TX

Re: Simple Machines B/Compound Machines C

Postby jkang » April 21st, 2015, 7:15 pm

http://img.sparknotes.com/content/testp ... pulley.gif
A problem I just came up with. Solved it and just want to make sure I'm right since I doubt my coach will know how to solve it (it's not that complicated).
In the diagram from the link, angle θ is 37 degrees and mass m is 15 kg. The coefficient of friction between mass m and the inclined plane is 0.4. Assume the pulley is frictionless. What are the maximum and minimum masses for mass M if the system is in equilibrium?
I got 4.235 kg <= M <= 13.82 kg? Got 4.235 kg by assuming left side was heavy, 13.82 by assuming right. With sig figs (mu only has one), 4 kg and 10 kg.
UT Austin '19
Liberal Arts and Science Academy '15


Return to “2015 Lab Events”

Who is online

Users browsing this forum: No registered users and 1 guest