Question

A student sitting on a stool is holding two 3 kg blocks next to her body such that the total moment of inertia for the student, stool and blocks is I₁ = 0.9 kg m². She is spinning at a rate of ω₁ = 4 radians/second. Feeling a bit sick, and understanding physics, she extends her (massless) arms moving the blocks from the initial position R₁ = 0.2 m to a distance R₂ = 0.75 m.

1)

Compare K₁, the total kinetic energy of the girl, stool and blocks when the blocks are next to her body, to K₂, the total kinetic energy of the girl, stool and blocks when the blocks are extended away from her body.

K ₁ < K₂

K ₁ = K₂

K ₁ > K₂

2) What is the angular velocity of the student when her arms are extended?

ω₂ = 0.284 radians/second

ω₂ = 1.07 radians/second

ω₂ = 2.07 radians/second

ω₂ = 0.842 radians/second

ω₂ = 0.892 radians/second

3) The student gets tired of holding the blocks and lets them drop. Compare ω₂ her angular velocity with the blocks held out, to ω₃ her angular velocity after dropping the blocks.

ω₂ < ω₃

ω₂ = ω₃

ω₂ > ω₃

Answer 1