A record turntable of radius R rotates at angular velocity w (Fig. 12.15). The circumference is presumably

Question:

A record turntable of radius R rotates at angular velocity w (Fig. 12.15). The circumference is presumably Lorentz-contracted, but the radius (being perpendicular to the velocity) is not. What's the ratio of the circumference to the diameter, in terms of π and R? According to the rules of ordinary geometry, that has to be π. What's going on here?