Fluid Mechanics 4.4 Flashcards
What is drag ?
It’s a resistance force that will slow something down. It’s a combination prof air resistance and friction
Give examples of how performers will try to minimise drag
- Swimmers will shave their whole body to reduce drag
- Wear tight fit clothing and streamline helmets in cycling
What is surface drag ?
Friction between surface of an object and the fluid environment
Eg swimmers: smooth tight suits and all body hair shaven making them more streamline
What is form drag ?
It’s the impact of the fluid environment of an object
Factors that reduce & increase drag
- ) Velocity of the moving body
- ) Cross sectional area of the moving body
- ) Shape/surface of the moving body
Velocity of the moving body greater velocity …
Greater velocity of a body through fluid, the greater the drag force
Describe 4 ways in which a cyclist reduces drag
Helmet: designed to encourage laminar flow
Bike: lightweight carbon fibre frame, aerodynamic features
Body position: Head over the bars, low over front wheel, arms tucked
Clothing: Compressed clothing
What is streamlining?
It is has shaping a body so it can move through fluid effectively and quickly, enables air flow smoothly and reduces fluid drag
What is turbulent ?
Flow in which the fluid undergoes irregular fluctuations and constantly undergoing changes in magnitude or direction. Increase fluid drag and friction and decreases velocity
What is laminar ?
Layers of fluid flow slide smoothly over one another
Undertake smooth paths and less resistance to movement
What will a large cross sectional area do (in terms of drag)
Increase drag
2 ways in which a skier can reduce their cross sectional area ?
Crouching low
Tucking arms in
What is the Bernoulli principle ?
Increase in the speed of a fluid occurs as a result of a decrease in pressure
Give an example of Bernoulli principle
Discuss is thrown, it experiences upward lift force, upward lift enables the discuss to stay in the air longer. This will increase horizontal displacement
What is lift force ?
Causes a body to move perpendicular to the direction of travel
