4.4 Fluid Dynamics Flashcards Preview

A-Level P.E Mrs Rex Year 2 > 4.4 Fluid Dynamics > Flashcards

Flashcards in 4.4 Fluid Dynamics Deck (19)
Loading flashcards...
1
Q

What is a dynamic fluid force?

A

Movement of liquid and gases, e.g. drag and lift

2
Q

What is drag?

A

Drag is a resistant force, acting in opposition to the direction of motion and has a negative effect on velocity. Drag is caused by a body travelling through a fluid.

3
Q

Drag is a combination of……….

A

Air resistance and friction.

4
Q

What are the two types of drag?

A

-Surface
-Form

5
Q

What is surface drag?

A

Surface drag is friction between surface of an object and the fluid environment.

6
Q

What is form drag?

A

Form drag is the impact of the fluid environment of an object…..Forces affecting the leading edge of an object increases form drag……Forces affecting the trailing edge of an object reduces form drag.

7
Q

What is streamlining?

A

Shaping a body so it can move through fluid effectively and quickly.

8
Q

What are the characteristics of streamlining?

A

-Incorporate a ‘gradual taper’
-Enables air flow smoothly
-Reduces fluid drag

9
Q

What is turbulent flow?

A

Flow in which the fluid undergoes irregular fluctuations, or mixing, constantly undergoing changes in magnitude and direction.

It increases fluid drag + friction and decreases velocity

10
Q

What is laminar flow?

A

When layers of fluid flow slide smoothly over on another.

They undertake smooth paths, or layers and are less resistant to movement.

11
Q

What are the 3 factors that reduce/increase drag?

A

1) Velocity of the moving body.
2) The cross-sectional area of the moving body.
3) The shape/surface of the moving body.

12
Q

How does the velocity of the moving body effect drag?

A

The greater the velocity of a body through a fluid, the greater the drag force.

13
Q

How does the cross-sectional area of the moving body effect drag.

A

A large cross-sectional area will increase drag. While a small cross-sectional area will decrease drag.

14
Q

How does the shape and surface characteristics effect drag?

A

A more streamlined, aerodynamic shape reduces drag.

15
Q

What does Bernoulli’s theory suggest?

A

An increase in the speed of a fluid occurs as a result of a decrease in pressure.

16
Q

What is lift force?

A

A force causing a body to move perpendicular to the direction of travel.

17
Q

How is a lift force achieved in discus?

A

Air that travels further and therefore faster has a low pressure (above the discus).

While air that travels shorter and therefore slower has a high pressure (below the discus).

A pressure gradient is formed as air always moves from high to low pressure. Causing an upwards lift and greater horizontal displacement.

18
Q

What is the use of a downward lift force?

A

By pushing the object/body in to the ground, greater frictional forces are created.

19
Q

How can downward lift be explained through an F1 spoiler.

A

-Due to angle of spoiler, air travelling over the top has a shorter distance
-The air above travels at a slower velocity, meaning it also has high pressure.

-Air travelling underneath has a longer distance.
-The air below travels at a greater velocity and the fire has a low pressure.