Fluid Flow Bernoullis Equation PHYS116 A01 4510 Lecture

Fluid Flow, Bernoulli’s Equation PHYS-116 A-01, 4/5/10, Lecture 33 Momchil Velkovsky

A block of ice (density 920 kg/m 3) and a block of iron (density 7800 kg/m 3) are completely submerged in a fluid. Both blocks have the same volume. Which block experiences the greater buoyant force? 1. 2. 3. 4. A. the block of ice B. the block of iron C. Both experience the same buoyant force. D. The answer depends on the density of the fluid.

Surface tension • How is it that water striders can walk on water (although they are more dense than the water)? dx l A F

Fluid flow I • The flow lines at the 3 left pictures are laminar. • The flow at the top of the right picture is turbulent.

Fluid flow II • The incompressibility of fluids allows calculations to be made even as pipes change.

Bernoulli’s equation • Bernoulli’s equation allows the user to consider all variables that might be changing in an ideal fluid.

Water pressure in a home d 1=2 cm, d 2=1 cm, P 1=4 x 105 Pa v 2=? , p 2=? , d. V 2/dt=?

An incompressible fluid flows through a pipe of varying radius P (shown in cross-section). Compared to the fluid at point radius 2 R P, the fluid at point Q has 1. 2. 3. 4. 5. ½ of the speed the same speed twice the speed four times the speed none of the above Q radius R

An incompressible fluid flows through a pipe of varying radius P (shown in cross-section). Compared to the fluid at point radius 2 R P, the fluid at point Q has 1. 2. 3. 4. 5. Q radius R greater pressure and greater volume flow rate. greater pressure and the same volume flow rate. the same pressure and greater volume flow rate. lower pressure and the same volume flow rate. none of the above

Speed of efflux (Bernoulli’s Equation III)

The Venturi meter (Bernoulli’s Equation IV)

Lift on an airplane wing

Viscosity and turbulence • When we cease to treat fluids as ideal, molecules can attract or repel one another—they can interact with container walls and the result is turbulence.

A curve ball (Bernoulli’s equation applied to sports) • Bernoulli’s equation allows us to explain why a curve ball would curve, and why a slider turns downward.

Reading for next time • Chapter 15. 0 -15. 4 • Problems 14. 83, 14. 87, 14. 92, 14. 98