# Children on a Merry go Round

1. Mar 29, 2012

### eagles12

1. The problem statement, all variables and given/known data

Two children ride on the merry-go-round. Child 1 is 2.0m from the axis of rotation, and child 2 is 1.5m from the axis. If the merry go round completes one revolution every 4.1s, find the angular speed and the linear speed of each child.

2. Relevant equations

w=Δθ/Δt
T=2∏/w

3. The attempt at a solution

a=v^2/r
a=v^2/2

a=v^2/1.5

2. Mar 29, 2012

### tiny-tim

hi eagles12!

(try using the X2 button just above the Reply box )
yes, that's the acceleration

but the question asks only for ω and v

3. Mar 30, 2012

### eagles12

im a little confused on how to find θ

4. Mar 30, 2012

### tiny-tim

so θ = one revolution = 2π

5. Mar 30, 2012

### eagles12

so I do w=2π/(1/4.1) and I got 25.76 but that is incorrect

6. Mar 30, 2012

### eagles12

is the angular speed for each kid the same? im not sure how the mass factors in, or is that just factored into the linear velocity?

7. Mar 31, 2012

### tiny-tim

hi eagles12!

(just got up :zzz:)
ω is (angular) speed, so it's (angular) distance over time …

in this case 2π/4.1
yes ω is the same for the whole of a rigid body, and for anything attached to it (like the kids)

mass is irrelevant, mass is physics

finding the angular or linear velocity from the time and angle etc is just geometry (maths) …

you won't need the mass until you start finding the force