Fluid mechanics Flashcards
1
Q
What is the definition of fluid mechanics ?
A
The study of an object or human body that travels through a liquid or gas
2
Q
What is dynamic fluid force ?
A
- The movement of liquids and gases
- For example: Drag and lift
- This effects :
- swimming, cycling, sprinting (drag)
- Javelin and discuss (drag and lift
3
Q
What are the two different types of drag ?
A
- Surface drag
- Form drag
4
Q
What is drag ?
A
- will slow something down
- resistance force
- caused by a body moving through liquid
- acts in the opposition to direction of movement
- negative effect on velocity
- combination of air resistance and friction
5
Q
What is surface drag ?
A
- friction between surface of an object and the fluid environment
6
Q
What is form drag ?
A
- The impact of a fluid environment on 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
How do cyclist reduce drag ?
A
- By streamlining using a slip stream
- Any cyclists behind the first cyclist get a reduced drag resistance
- Also helps if the gap between cyclists is close
8
Q
What was bernoullis main principle ?
A
Found an increase in the speed of fluid occurs due to a decrease in pressure
9
Q
What is a lift force ?
A
Causes a body to move perpendicular to the direction of travel
10
Q
Explain the Bernoulli principle with the discuss ?
A
- When the discuss is thrown, an upward force happens during flight
- A lift force enables the discuss to stay in the air for longer which increases the horizontal distance covered
11
Q
Why is the angle of attack important ?
A
- when a projectile is released the angle of attack changes the flow of air around the projectile
- So that the air that travels over the top has a longer distance to travel
12
Q
How does the pressure gradient affect Bernoulli’s principle ?
A
- The air above is travelling faster so has lower pressure
- The air below is travelling slower so creates a higher pressure
- The pressure gradient causes the lift as air travels from a high to low gradient
13
Q
What happens if the angle of attack is too big ?
A
- lift is reduced
- drag increases
- distance stop
14
Q
What is the purpose of a spoiler ?
A
- Due to the angle of a spoiler on a car, the air over the top has a shorter distance
- The air above travels at slower velocity and bigger pressure
- The air below travels at quicker velocity and lower pressure
15
Q
How does downward force affect a race car ?
A
- Greater friction forces between tyres and the track
- This lets the tires have a firm grip on the surfaces
- This allows the car to travel at faster speeds around the corner
- This gives the driver a faster time and a greater chance of success
