SAE No. 10 oil has a viscosity of 0.20 Pa-s. How long would it take to pour 4.0 L of oil through a funnel with a neck 15. cm long and 2.0 cm in diameter? (Assume the surface of the oil is kept 6.0 cm above the top of the neck, and neglect any drag effects due to the upper part of the funnel.)
A) 52 s
B) 84 s
C) 105 s
D) 1.5 minutes
E) 46 s

Question

Quizplus · Accepted Answer

Poiseuille's law: $$t=\frac{8\eta L}{ \pi r^4 g ho}V$$$$t=\frac{8(0.20 	ext{ Pa-s})(0.15 	ext{ m})}{\pi (0.010 	ext{ m})^4 (9.81 	ext{ m/s}^2)(850 	ext{ kg/m}^3)}(4.0 	imes 10^{-3} 	ext{ m}^3)$$$$t=52 	ext{ s}$$

SAE No 10 Oil Has a Viscosity of 0