A compact disc spins at 2.7 revolutions per second. An ant is walking on the CD and finds that it just begins to slide off the CD when it reaches a point 2.6 cm from the CD's center. (a) What is the coefficient of friction between the ant and the CD?
n=2.7 rev/s => ω=2πn=2•3.14•2.7 ≈17 rad/s
ma=F(fr)
mω²R=μmg
μ=ω²R/g =17²•0.026/9.8 =0.77