4 Fluids

Question 1

Pascal’s principle

Answer 1

change in pressure transmitted undiminished to all points of fluid to walls
(ex. hydraulic lift)

Question 2

Pascal’s equations

Answer 2

P = F(1) / A(1) = F(2) / A(2)

W = A(1)d(1) = A(2)d(2)
W = P deltaV

*dependent on conservation of energy

Question 3

Archimedes’ principle

Answer 3

buoyancy
submerged portion of solid displaces equal volume of liquid
mass of displaced water exerts force equal to its weight (m x a) against the floating object

Question 4

Archimedes’ equations

Answer 4

F(B) = p(fluid) V(obj, sub) g

mass of displaced fluid = p(fluid) V(obj, sub)

Question 5

sinking objects: F(g) ____ F(B)

Answer 5

greater

Question 6

floating objects: F(g) _____ F(B)

Answer 6

equal

Question 7

cohesion

Answer 7

molecules in middle of liquid experience equal attractive forces on any side

molecules on surface of liquid experience greater attractive force from within the liquid
(net force pulls them to center of liquid)

Question 8

adhesion

Answer 8

molecules in liquid are more attracted to surface of their container than other liquid molecules

Question 9

viscosity

Answer 9

measure of internal resistance to flow

*negligible in ideal fluids

Question 10

Poiseuille’s Law

equation

Answer 10

laminar flow

Q = (pi r^4 deltaP) / 8(viscosity)L

Question 11

turbulent flow

equation

Answer 11

when fluid reaches critical speed

v(c) = N(R) (viscosity) / p D

*laminar flow still occurs in boundary layer

Question 12

conservation of mass continuity equation

Answer 12

Q = V(1)A(1) = V(2)A(2)

Question 13

Bernoulli’s equation

Answer 13

(conservation of energy)

P(1) + (1/2) p v(1)^2 + pgh(1) = P(2) + (1/2) p v(2)^2 + pgh(2)