8. An estimate of the minimum velocity required for a round flat stone to skip when it hits the water is given by (Lyderic Bocquet, “The Physics of Stone Skipping,” Am. J. Phys., vol. 71, no. 2, February 2003):

where M and d are the stone mass and diameter, is the water density, C is a coefficient, is the tilt angle of the stone, is the incidence angle, and m/s2. Determine d if m/s. (Assume that kg,

, 1,000 kg/m3, and .)