Final answer:
The final speed of the cylinder's center of mass after 3 seconds is 13.1 m/s.
Step-by-step explanation:
To find the final speed of the cylinder's center of mass, we can use the principle of conservation of energy. The initial kinetic energy of the center of mass is given by 1/2 * M * (v^2), where M is the mass and v is the initial speed. The final kinetic energy is given by 1/2 * M * (vf^2), where vf is the final speed.
By setting the two equations equal to each other and solving for vf, we get vf =√(v^2 + 2 * g * h), where g is the acceleration due to gravity and h is the height the cylinder rolls down.
Plugging in the values, we get vf = √((9.0 m/s)^2 + 2 * 9.8 m/s^2 * 3.0 m) = 13.1 m/s.