how to convert rev/min to rad/s. please help?

Question

I get an answer of 11.2 rev/min and this could be the problem to me obtaining the proper answer or it could be my conversions. please help!

A playground merry-go-round of radius 2.00 m has a moment of inertia I = 230 kgm2 and is rotating about a frictionless vertical axle. As a child of mass 25.0 kg stands at a distance of 1.00 m from the axle, the system (merry-go-round and child) rotates at the rate of 14.5 rev/min. The child then proceeds to walk toward the edge of the merry-go-round. What is the angular speed of the system when the child reaches the edge?

Answer 1

One revolution = 2pi radians. One minute = 60 seconds. So 1 rev/min = 2pi/60 rad/s. Multiply 11.2 rev/min by 2pi/60 to get 1.17286 rad/s.

Answer 2

That seems about right: the rotational speed has decreased by less than half as the child moves twice the distance from the centre.

Does the moment of inertia of the merrygoround include the child?

(2 pi radians) / 60 is 1 rpm

Answer 3

1 rev is 2 pi radians. 1 min is 60 seconds

Answer 4

use dimensional analysis

14.5 rev 1 min 2 pi rad
------- * ----------- * -----------------
1 min 60 seconds 1 rev