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

[afcwestwarrior]

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

 

[tiny-tim]

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!

(have an omega: ω )

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

Now use rotational KE = (1/2)Iω²,

and PE + KE = constant.

 

[thomate1]

with the moment of inertia calculationYes, your calculation for the moment of inertia is correct. To find the initial kinetic energy, you can use the formula K = 1/2 * I * w^2, where I is the moment of inertia and w is the angular velocity. Since the rod is constrained to rotate about a horizontal axis, the angular velocity is equal to the linear velocity divided by the radius (w = v/r). So, the initial kinetic energy would be K = 1/2 * (.5 kg*m^2) * (1.2 m/s)^2 = 0.36 J.

To find the total angle of the rod coming to rest, you can use the formula K = 1/2 * I * w^2 again, but this time, the final kinetic energy would be zero since the rod has come to rest. So, you can solve for the final angular velocity and use the formula w = v/r to find the total angle. I hope this helps!