❌Fluid Mechanics

Question 1

What is fluid mechanics?

Answer 1

The study of an object or the human body that travels through any liquid or gas.
E.g. Swimmers through water. Tennis ball through air.

Question 2

What is fluid dynamics?

Answer 2

It’s concerned with the movement of liquids or gases.

Question 3

What are dynamic fluid forces?

Answer 3

Drag

Lift

Question 4

What is drag force?

Answer 4

It acts in opposition to motion.

Question 5

What does drag force do?

Answer 5

It slows something down.

It’s a resistance force.

Question 6

What is a drag force produced from?

Answer 6

Air resistance and friction.

Question 7

What are the two types of drag?

Answer 7

Surface drag

Form drug

Question 8

What is surface drag?

Answer 8

It relates to friction between the surface of an object and the fluid environment.
Sometimes called ‘skin drag’.

Question 9

How can you reduce surface drag?

Answer 9

Remove body air

Specialised clothing

Question 10

What is form drag?

Answer 10

Relates to the impact of the fluid environment on an object.

It’s sometimes called ‘shape drag’.

Question 11

What increases/decreases form drag?

Answer 11

The forces affecting the leading edge of an object increases form drag.

The forces affecting the trailing edge reduce form drag.

Question 12

What does a large form drag do?

Answer 12

Offers less turbulent air for anything that is following, e.g. in the slipstream.

Question 13

What’s an example of slipstreaming?

Answer 13

A cyclist will use another riders slipstream. As the wind hits the cyclist, it goes around the sides and the cyclist behind uses the air pocket that has been created.
For it to work, the second cyclist has to ride very close to the bike in front (approx 15-30cm).
The can save up to 30% more energy as a result.

Question 14

What are the factors the reduce and increase drag?

Answer 14

The velocity of the moving body.
The cross-sectional area of the moving body.
The shape and the surface characteristics of a moving body.

Question 15

What is streamlining?

Answer 15

Involves shaping a body so it can move as effectively and quickly through a fluid as possible.

Question 16

What is meant by the velocity of the moving body?

Answer 16

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

Question 17

What is an example of the velocity of the moving body affecting drag?

Answer 17

A racing car, sprinter, cyclist will experience greater air resistance in their competition, which increase drag.

Question 18

Why is it important to reduce the effects of drag?

Answer 18

Streamlining the body as much as possible.

Question 19

What is meant by the cross-sectional area of the moving body?

Answer 19

A large cross-sectional area increases drag.

A smaller one reduces drag.

Question 20

What’s an example of the cross-sectional area of the moving body affecting drag?

Answer 20

In the Tour de France, the competitors reduce their cross-sectional area by crouching low over the handlebars, rather than sitting upright. This allows drag to be reduced and increases their speed.

Question 21

What is meant by the shape and the surface characteristics of a moving body?

Answer 21

A more streamlined, aerodynamic shape reduces drag.

Question 22

What’s an example the shape and the surface characteristics of a moving body affecting drag?

Answer 22

Speed skier - helmet that extends to their shoulders to give them a more streamlined position and their special form-fitting suit and aerodynamic boots are also streamlined.

Cycling - clothing with ridges and an aerodynamic helmet with air ducts have recently been designed to try to reduce the effects of drag even more.

Swimmers - shave off all their body hair and wear half-body swimsuits so they create a smooth surface. Swim caps can also been worn is people don’t shave their heads.