2.1 INTRO TO FLUID FLOW

Question 1

What is Newton’s first law of motion?

Answer 1

Unless a force acts on a body, its velocity will not change.

If F=0, then change in u=0

Provides intuitive meaning of force: that agent which CHANGES the velocity of a body

Question 2

What is Newton’s second law of motion?

Answer 2

The rate of change of momentum (mu) of a body, is proportional to the force that acts on it.

F = m.a

Question 3

What is Newton’s third law of motion?

Answer 3

For any force exerted, there is an equal force in the opposite direction.

Question 4

What is viscosity?

Answer 4

A measure of the resistance of a fluid to deformation e.g. shearing or extension.
(Simply, the resistance of a fluid to flow)

Question 5

How do you obtain the kinematic viscosity v (nu)?

Answer 5

Divide the dynamic viscosity by density.

L^2T^-1 (L^2/T)

It is the ratio of dynamic viscosity to fluid density.

SI base units: kg m^-1 s^-1

Question 6

What is the Bernoulli effect?

Answer 6

• Fluid velocity varies inversely with fluid pressure
• Demonstration with balloons; U2 > U1, P2>P1
• The sum of a pressure term, a velocity term and a gravitational/height term remain constant