A flea stands on the end of a 1.0 cm long sweep second hand of a clock that rests
horizontally on a table. What is the minimum
coefficient of static friction which would
allow the flea to stay there without slipping?
Include an appropriate free-body diagram.

The rotation speed, w, is 2*pi radians/60 seconds = 0.105 rad/s and r = 0.01 m

The flea needs centripetal force given by

Fc = m*w^2/r

That force must come from friction given by

Ff = mu*N = mu*m*g

So

m*w^2/r = mu*m*g

Substitute the data, cancel the m's, and solve for mu.

b

explanation:

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.