Merry Go Round (Linear Speed)

kaylanp01

1. The problem statement, all variables and given/known data
A rotating merry-go-round makes one complete revolution in 3.80 s. What is the linear speed of a child seated 1.24 m from the center?

2. Relevant equations
vt = wr
w = 2(pi)/T
Vt = 2(pi)r/T

3. The attempt at a solution
I know that the further you are from the center, the higher velocity that you'll have, but I'm not sure where to go with that.

tiny-tim

Homework Helper
A rotating merry-go-round makes one complete revolution in 3.80 s. What is the linear speed of a child seated 1.24 m from the center?
Hi kaylanp01!

hmm … let's try an easy case …

how far does the child go in 3.80s?

LowlyPion

Homework Helper
You derived the equation, so just plug in your numbers.

kaylanp01

You derived the equation, so just plug in your numbers.
So thats the equation for linear velocity? I'm confused. I just grabbed that out of my notes.

kaylanp01

Hi kaylanp01!

hmm … let's try an easy case …

how far does the child go in 3.80s?
Wellll...technically...he doesn't go anywhere, as he ends up in the same place ;).

LowlyPion

Homework Helper
So thats the equation for linear velocity? I'm confused. I just grabbed that out of my notes.

The trick now is to understand what you took notes about then isn't it.

kaylanp01

The trick now is to understand what you took notes about then isn't it.
I'm just trying to get through it now...try to pass the CAPA part of the course even if I can't pass the exam. haha. It says in my notes that the equation I derived above was for tangential v...so are tangential and linear the same thing?

LowlyPion

Homework Helper
I'm just trying to get through it now...try to pass the CAPA part of the course even if I can't pass the exam. haha. It says in my notes that the equation I derived above was for tangential v...so are tangential and linear the same thing?
Yes tangential V is linear V.

kaylanp01

Yes tangential V is linear V.
Okay, great.
I looked at that website, and it eliminates my next question (I was going to ask how to calculate acceleration, but its all there) so you just saved me (and yourself) from more pain. haha.
Thank you (twice). :)

kaylanp01

Yes tangential V is linear V.
Okay. I've been defeated. I still can't get acceleration.
I used a = 2.05/1.24 = 1.65 and thats not correct.

LowlyPion

Homework Helper
The acceleration is the centripetal acceleration v2/r

kaylanp01

The acceleration is the centripetal acceleration v2/r
So how will I know when its centripetal and when it isn't? I'm so confused. :(

LowlyPion

Homework Helper
So how will I know when its centripetal and when it isn't? I'm so confused. :(
If it is undergoing circular motion its mass is undergoing centripetal acceleration.

When the disk is changing ω at some rate of increase that is called α, and it is called angular acceleration.

kaylanp01

If it is undergoing circular motion its mass is undergoing centripetal acceleration.

When the disk is changing ω at some rate of increase that is called α, and it is called angular acceleration.
Okay, its a little more clear now. I'm going to go study until my eyes water and/or begin to blur. Any study tips to offer?

LowlyPion

Homework Helper
Okay, its a little more clear now. I'm going to go study until my eyes water and/or begin to blur. Any study tips to offer?

kaylanp01

Thankfully, I won't be doing another physics course after this term. I usually read ahead throughout the semester, but really got off track within the past few weeks. Luckily, I currently have an A, so I can afford to do not-so-well on the final. ha.

LowlyPion

Homework Helper
Good luck on the exam then.

Cheers.

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