Wednesday, 10 October 2007 - 7:41 PM EDT

I'm in. I say we start working on the problems this weekend. like Suday night or so (so a bunch of people can be on at the same time ).

Thursday, 11 October 2007 - 2:59 AM EDT

CeF you are a smart thinker. this is very insightful, i for one im fed up totally with all those emails. this is way easier

Thursday, 11 October 2007 - 7:40 AM EDT

Amen to that... I hate all those damn emails. 

Oh and what a total waste of time lecture is. That class annoys me.  

Friday, 12 October 2007 - 9:33 AM EDT

Great idea! i hate those emails.  Ill get on sunday night also.  If anyones recitation instructor sucks, I would go to the russian lady with the red hair.  She helps you out with all the problems.

Friday, 12 October 2007 - 11:20 PM EDT

Ive done all the Capas, except the conceptual. If anyone has those, id live to know what im doing wrong. let me know which of the others anyone needs help with

Sunday, 14 October 2007 - 1:37 AM EDT

I was trying to do the very first problem ( finding the angular velocity) and all it supposed to be is the v/r right?  an to change rpms to radians/second is just 2pi * rpms/ 60.  So for this problem why isnt the answer 70.41 rads/sec. and yes i did divide te diameter by 2

Sunday, 14 October 2007 - 9:22 PM EDT

You just need to find radians per second from revolutions per minute.  You don't need to do anything with the radius of the wheel.

1606 rev/min x 1 min/60 sec x 2pi rad. = rad/sec

Sunday, 14 October 2007 - 9:41 PM EDT

anybody got the conceptual part?

Sunday, 14 October 2007 - 9:46 PM EDT

These are my conceptual answers:

Two objects of equal mass are on a turning wheel. Mass 1 is located at the rim of the wheel while mass 2 is located halfway between the rim and the axis of rotation. The wheel is rotating at a constant angular velocity. For each of the following statements select the correct option.
Greater Than: The radial acceleration of mass 1 ____ the radial acceleration of mass 2.
Equal To: For a given time, the angle covered by mass 2 is ____ mass 1.
Greater Than: The moment of inertia of mass 1 is ___ the moment of inertia of mass 2. (Both moments of inertia are taken about the axis of rotation.)
Less Than: For a given time, mass 2 travels a distance ____ mass 1.
Equal To: The tangential acceleration of mass 1 ____ the tangential acceleration of mass 2.
Greater Than: The speed of mass 1 is ____ mass 2. 

Goodluck, bitches 

Sunday, 14 October 2007 - 9:54 PM EDT

Here is the conceptual of another classmates:

Two objects of equal mass are on a turning wheel. Mass 1 is located at the rim of the wheel while mass 2 is located halfway between the rim and the axis of rotation. The wheel is rotating at a constant angular velocity. For each of the following statements select the correct option.
Greater Than: For a given time, mass 1 travels a distance ____ mass 2.
Equal To: The tangential acceleration of mass 1 ____ the tangential acceleration of mass 2.
Equal To: For a given time, the angle covered by mass 2 is ____ mass 1.
Less Than: The speed of mass 2 is ____ mass 1.
Greater Than: The moment of inertia of mass 1 is ___ the moment of inertia of mass 2. (Both moments of inertia are taken about the axis of rotation.)
Greater Than: The radial acceleration of mass 1 ____ the radial acceleration of mass 2. 

Sunday, 14 October 2007 - 11:11 PM EDT

Hey I have everything but part c of the cyclist and the rotating chair. I can help with anything else if anyone needs it. if anyone knows how to do these can you please help?

Sunday, 14 October 2007 - 11:35 PM EDT

ok nevermind, i got the rotating chair... all i need is part c of the cyclist. let me know if you guys need help on anything else

Monday, 15 October 2007 - 8:45 PM EDT

Hey B. Will you help me with the rotating chair and the flywheel trucks

Tuesday, 16 October 2007 - 12:19 AM EDT

Two objects of equal mass are on a turning wheel. Mass 1 is located at the rim of the wheel while mass 2 is located halfway between the rim and the axis of rotation. The wheel is rotating at a constant angular velocity. For each of the following statements select the correct option.
Less Than: The moment of inertia of mass 2 is ___ the moment of inertia of mass 1. (Both moments of inertia are taken about the axis of rotation.)
Equal To: The tangential acceleration of mass 2 ____ the tangential acceleration of mass 1.
Equal To: The angular velocity of mass 1 is ____ the angular velocity mass 2.
Greater Than: The radial acceleration of mass 1 ____ the radial acceleration of mass 2.
Equal To: For a given time, the angle covered by mass 1 is ____ mass 2.
Greater Than: For a given time, mass 1 travels a distance ____ mass 2.

here ya go guys

Tuesday, 16 October 2007 - 2:27 AM EDT

I only have the first two and the conceptual problem. I either have no idea where to start on the rest or have no idea what I'm doing wrong.

 If anyone would like to help, I'd appreciate it.

Tuesday, 16 October 2007 - 9:04 AM EDT

Hey will someone please help me with the cyclist (all parts) & flywheel in trucks (B).

Tuesday, 16 October 2007 - 11:23 AM EDT

what units are we suppose to use for part a of the merry-go-round problem?

Tuesday, 16 October 2007 - 11:37 AM EDT

Merry Go Round part A I think you use "m*N". Can you explain how to do it? I can't get it.

Tuesday, 16 October 2007 - 11:44 AM EDT

Flywheel in Trucks part B

 I multiplied my kW by 1000 and divided that from my J from part A. Then I divided by 60 (seconds in a minute) to get the minutes.

Can you explain how to do the other Cyclist parts?

Tuesday, 16 October 2007 - 11:47 AM EDT

My bad on asking for the Cyclist. Can you help me with the Circular Platform?

Tuesday, 16 October 2007 - 2:17 PM EDT

I need help on 4 things, the second part of the merry go round, the Belt drive, rotating chair and Circular Platform if anyone can help me with any of these i have all the others!  Thanks guys..

Tuesday, 16 October 2007 - 2:35 PM EDT

If you go to the power point from Mondays lecture on the physics website the very last slide is the circular platform problem, if anyone knows how to do the 2nd part of the rotating chair it would help me out alot! :)

Tuesday, 16 October 2007 - 6:27 PM EDT

Thanks!..Now i just need the drive belt and chair, oh and the last part of te merry go round. 

Tuesday, 16 October 2007 - 6:30 PM EDT

hey... notgoodphysicsdude.... i'm curently working on the circular platform,  but if anyone has it please help us.

Tuesday, 16 October 2007 - 6:47 PM EDT

just follow the last page of mondays lecture and plug your numbers in, and it should work...

find I-initial and Ifinal then once you find those  you use them in

Wi X (Ii/ If) 

Tuesday, 16 October 2007 - 6:49 PM EDT

did anyone figure out the Torque/Merry go round, Belt Drive, or rotating chair problems? i have all the others but those are really stumping me, thanks.

Tuesday, 16 October 2007 - 6:51 PM EDT

Yup it does work

Tuesday, 16 October 2007 - 7:37 PM EDT

for rotating chair part A): (Ii / If) times Wi = the answer in rad/s.  I don't have part B) yet

Tuesday, 16 October 2007 - 7:41 PM EDT

For rotating chair part B) a girl said to use .5*L(Wf-Wi) = KE. But its not working for me... let me know if this works for yall.

Tuesday, 16 October 2007 - 8:08 PM EDT

bb,

do

.5 x L x (Wf -Wi)

L= Ii x Wi

answer should be in Joules. 

Tuesday, 16 October 2007 - 8:26 PM EDT

thanks "M". does anyone know how to do the belt drive and the merry-go-around.

Tuesday, 16 October 2007 - 8:30 PM EDT

cant figure out merry go round  at all...its making me nuts.

belt drive:

(Ra/ Rc)  x Acceleration =

then do  the rev/min x 2pi/60 = ____ rad/s

and divide your  rad per sec/ first answer.....answer in Seconds

let me know if you get that merry go round one lol

Tuesday, 16 October 2007 - 8:43 PM EDT

I will let you know if I get it.  Do you need anything else?

Tuesday, 16 October 2007 - 8:48 PM EDT

Merry Go round part A:  (1/2*mass(merry-go-round)*Radius^2 ) + (2(MAss of child)*Radius^2)

 Then converty the Rpms.  (2Pi*rpm/60) and divide by your time.

Then FINALLY Multiply your answers for both parts and the answer is in m*N.

Hope we can get part B now..

Tuesday, 16 October 2007 - 9:11 PM EDT

Hey will someone please help me with part a of flywheel in trucks and the cyclist....i am so lost!! Thanks

Tuesday, 16 October 2007 - 9:13 PM EDT

for part B of the Merry Go Round you just take the answer from part A and divide it by the radius to get the answer.

Tuesday, 16 October 2007 - 9:54 PM EDT

Hey hey....

 What are the units for the merry go round part b

Also does anyone have circular performance, cyclist, or flywheel part A?

 Please any help would be great, I am freaking out!!!!!

 Thanks lol

Tuesday, 16 October 2007 - 9:57 PM EDT

The units for Merry-Go-Round Part A are Newtons. 

part 1) multiply revolutions by 2pi to get theta. then plug theta into equation theta=w0t+ 1/2(angular accleration)(t)^2 to get angular acceleration. remember w0t=0 because initial velocity is zero. then get angular velocity by plugging the accleration into equation w=w0 +(acceleration)(t). now for part 3:

take your answer you got in part 2 (angular velocity) of wheels and multiply it by the radius of wheels in  meters. That is your velocity, now take your answer 1 (angular acceleration) and multiply it by the radius as well, that is your acceleration. Now take your velocity and acceleration and plug those into the kinematic equation v^2= 2ax where you are finding x, so all you do is square velocity and divide that by 2 times the accleration, you get your answer in meters. 

 The Flywheel problem is the only one I have left.

Tuesday, 16 October 2007 - 9:58 PM EDT

Lmao. That description to solve a problem that I posted is for the Cyclist. 

Tuesday, 16 October 2007 - 10:25 PM EDT

Does anyone know the units for part a of flywheel?

Tuesday, 16 October 2007 - 10:48 PM EDT

Hey guys i finished all of them but circular platform so if anyone could help me that would be great! Thanks

Tuesday, 16 October 2007 - 10:51 PM EDT

The Circular Platform is on the last slide of the last Powerpoint posted on the Physics page. 

Tuesday, 16 October 2007 - 10:52 PM EDT

Thanks!!

Tuesday, 16 October 2007 - 11:13 PM EDT

How do you solve the angular acceleration problem?  is it not  given rpm/60 then that answer divided by your given seconds?

Wednesday, 17 October 2007 - 12:07 AM EDT

Anyone have the Truck Flywheel Part b? 

I tried this:

Name: "notgoodphysicsdude"

Flywheel in Trucks part B

 I multiplied my kW by 1000 and divided that from my J from part A. Then I divided by 60 (seconds in a minute) to get the minutes.

(8.7KWx1000)/part a 5.1x10^7= blah.... then divide that by 60

Am i doing something wrong?

It's giving me a tiny number that doesn't really make any sense. 

Any help would be appreciated.  

Wednesday, 17 October 2007 - 12:14 AM EDT

Name: user-01

How do you solve the angular acceleration problem?  is it not  given rpm/60 then that answer divided by your given seconds?

RPM divided by 60. Multiply by 2pi= initial Rad/s

(Final Rad/s - initial Rad/s) / Seconds= accel in rad/s^2

Final Rad/s = rest = 0

answer should be negative. Don't forget to put that sign in when entering it into capa.  

Sunday, 21 October 2007 - 2:56 PM EDT

does anyone remember how they did part b of the car accident problemin CAPA #6?

Wednesday, 24 October 2007 - 9:05 AM EDT

anyone know how to do collision inelastic problem for the mini exam?