2 physics questions about revolutions and speed in centripetal acceleration?

Question

1. A sample of blood is placed in a centrifuge of radius 13.0 cm. The mass of a red blood cell is 3.0  10-16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0  10-11 N. At how many revolutions per second should the centrifuge be operated?

2. A 2000 kg car rounds a circular turn of radius 17 m. If the road is flat and the coefficient of friction between tires and road is 0.74, how fast can the car go without skidding?

Ossi G · Accepted Answer

Hello

1)

F = mω^2R where ω = angular velocity
ω^2 = F*R/m 
w^2 = 4*10^-11*0.13/(3*10^-16) 
ω = 131.656 rad/s

ω = 2pif 
f = ω/(2pi)
f = 131.656/(2pi)
f = 20.953 rps

2)

centrifugal force = friction force

mv^2/R = mgμ
v^2 = Rgμ
v^2 = 17*9.81*0.74 
v = 11.108 m/s  <- max velocity

Regards

2 physics questions about revolutions and speed in centripetal acceleration?

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