Two metal disks, one with radius R1 = 2.41 cm and mass M1 = 0.790 kg and the oth

Question

Two metal disks, one with radius R1 = 2.41 cm and mass M1 = 0.790 kg and the other with radius R2 = 4.85 cm and mass M2 = 1.69 kg are welded together and mounted on a frictionless axis through their common center.

1.) What is the total moment of inertia of the two disks? I did figure out this answer :-)

I = 0.0022   

2.) A light string is wrapped around the edge of the smaller disk, and a 1.50-kg block, suspended from the free end of the string. If the block is released from rest at a distance of 2.07 m above the floor, what is its speed just before it strikes the floor?

v = ?? m/s

3.) Repeat the calculation of part B, this time with the string wrapped around the edge of the larger disk.

v = ?? m/s

I have NO IDEA how to do these problems. Please show step by step with correct answers so I can try to understand.

THANK YOU!!

Explanation / Answer

hey,ill explain the steps try in that way

simply by conservation of energy

1)we can calculate V by conservation of energy
ie kinetic energy rotational+kinetic ebegy translational=potential energy initial
1/2*I*w^2+1/2*m*V^2=mg*2.07

1/2*V^2(I*(1/R^2)+m)=m*g*2.07
Where W*R1=V that is w(angular velocity)*R=Velocity(translational)

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