I need to to find the moment of inertia for the system

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SUMMARY

The discussion centers on calculating the moment of inertia for a system comprising a 2 kg uniform rod and two point masses (1.5 kg and 0.5 kg) attached at either end. The correct formula for moment of inertia, I, is applied as I = m(r)^2, where the radius r is 0.5 m. The initial calculation of I = 0.5 kg*m² is confirmed as correct, but it is noted that the moment of inertia of the rod itself must also be included. The next steps involve calculating the initial kinetic energy using the formula for rotational kinetic energy and applying the conservation of energy principle.

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afcwestwarrior
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Homework Statement



2 kg uniform rod of length 1m is constrained to rotate about a horizontal axis passing through its center. The rod has a 1.5 kg point mass attached to one end and a 0.5 kg point mass attached to the other end. The 1.5 kg mass is given a downward push so that it starts moving with an initial velocity of 1.2 m/s.


Ok I used the equation of moment of inertia or rotational inertia
I=m(r)^2


Here's what I did
m1=.5 kg
m2=1.5 kg
M=2kg
r=1/2 because L =1m and the center of mass is in the middle of the rod
thus I plugged in the variable

I=.5(1/2)^2 +1.5(1/2)^2
=.5 kg*m^2

is that right

and next i have to find the initial kinetic energy and then i have to find the total angle of it coming to rest. I need help
 
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afcwestwarrior said:
2 kg uniform rod of length 1m is constrained to rotate about a horizontal axis passing through its center. The rod has a 1.5 kg point mass attached to one end and a 0.5 kg point mass attached to the other end. The 1.5 kg mass is given a downward push so that it starts moving with an initial velocity of 1.2 m/s.

I=.5(1/2)^2 +1.5(1/2)^2
=.5 kg*m^2

is that right

and next i have to find the initial kinetic energy and then i have to find the total angle of it coming to rest.

Hi afcwestwarrior! :smile:

(have an omega: ω :wink:)

Yes, your I is right … but don't forget to add on the I of the rod itself! :wink:

Now use rotational KE = (1/2)Iω2,

and PE + KE = constant. :smile:
 

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