# A child stands on the edge of a merry-go-round

1. Oct 18, 2012

### joe426

1. The problem statement, all variables and given/known data
A 15 kg child stands on the edge of a small merry-go-round of radius 2.0 m. If the merry-go-round turns at a steady rate of 11 rpm, calculate the magnitude and direction of the net force
on the child.

2. Relevant equations
I'm thinking FG = G(m/r2)

3. The attempt at a solution
FG = 11(15/2^2)
= 41.25

The direction would be clockwise?

2. Oct 18, 2012

### Nytik

For circular motion, F = mrω^2

ω = 2π/T where T is the time period for one rotation.

Also, the force in circular motion always points in a particular direction. Do you know it?

3. Oct 18, 2012

### joe426

So it would be,

F= (15)(2)(2π/11)^2
F= 9.7N

The force in circular motion always points towards the center or rotation.

4. Oct 18, 2012

### Nytik

Almost, but you have to convert your value for T into the correct units first. It might be easier to use ω = 2πf, where frequency is revolutions per second.

5. Oct 18, 2012

### joe426

f= (15)(2)(2π(11/60))^2
f= 30 * (2π * .183)^2
f= 34n

6. Oct 18, 2012

### Nytik

The equation is correct but I think you forgot to square the bracket.

7. Oct 18, 2012

Oops.