Chapter 6 - Force and Motion-II - Problems - Page 144: 55

$F = 2600~N$

It takes 8 flashes to complete one circle. We can find the period $T$: $T = (8)(\frac{1.0~s}{2000}) = 4.0\times 10^{-3}~s$ We can find the speed $v$: $v = \frac{2\pi~r}{T}$ $v = \frac{(2\pi)~(0.035~m)}{4.0\times 10^{-3}~s}$ $v = 55~m/s$ We can find the force on the bolt: $F = \frac{mv^2}{r}$ $F = \frac{(0.030~kg)(55~m/s)^2}{0.035~m}$ $F = 2600~N$