can anyone help with a physics question??? A ball with mass 0.200kg on a string is being rotated around with an angular velocity of 12.0 rad/s at a radius of 12.5cm. The radius is suddenly decreased to 7.25 cm. What is the new angular velocity? (hint: the moment of inertia for a particle in rotation about a center point is I = mr^2)

Question

can anyone help with a physics question???    A ball with mass 0.200kg on a string is being rotated around with an angular velocity of 12.0 rad/s at a radius of 12.5cm. The radius is suddenly decreased to 7.25 cm. What is the new angular velocity? (hint: the moment of inertia for a particle in rotation about a center point is I = mr^2)

anonymous · Answer

radius must be measure in meters not in cm so first convert that

anonymous · Answer

$$KR=\frac{1 }{2 } I ^{2}$$ using this equation we can find the rotational
energy. and we know how to find I using$$I=mr ^{2}$$ so its plug and chug first find the inertia for the given information. I=0.003125 kg*m^2. plug that into the KR equation. and find that KR = 0.225 that now equals the new KR value for the new angular velocity.