Calculating Rotational Energy Levels for a Caroussel: How Do I Proceed?

[leopold123]

Hello forum members...
I have a problem in calculating the energy of rotational levels. Kindly help me...The question goes like this:

A Caroussel(merry-go-round) of diameter 20 m and weight 1 ton( =1000 kg that is evenly distributed on the discs) rotates 10 times per minute. Calculate the energy of rotational levels and the angular moment quantum number.

Well, the energy of rotational levels is given as:

E=BJ(J+1); B is the rotational constant which is given as, B=h^2/8π^2Iand J=0,1,2...

Since i know the mass of the object and the diameter, i could calculate the moment of inertia I using I=mr^2, r is the radius. so my I= 100000kg/m^2

I don't know what to do now. How should i proceed further to calculate the energy of rotational levels?...Please help me... Thanks...:)

 

[Borek]

Forget about "rotational levels" for a moment.

What is the energy of the merry-go-round in terms of classical physics?

 

[leopold123]

i assume that would be the kinetic energy, K.E= L^2/2I

 

[Borek]

Good. Can you calculate J for that value?

 

[leopold123]

I am sorry...I cant...could you show me, please?

 

[leopold123]

Could you please show me how can one calculate the j values?...please

 

[Borek]

Just plug everything into the given equation and solve for J, there is no magic in there, just a simple high school algebra. You are expecting something difficult and it blinds you.

 

[leopold123]

ok...does this mean that I am supposed to find out K.E using K.E=L^2/2I and plug this value in E=BJ(J+1)?...I can find out B because i know inertia...so i have B, I and if i find K.E, i ll get J...thats what you mean, don't you?

 

[Borek]

Yes, this is a simple plug and chug.