FLUIDS What is a Fluid? a substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid. Fluids are able to flow easily. Liquids, such as, water running out of a tap, syrup being poured out of a container and gasoline flowing through a gas line in an engine are examples of fluids. We also need to understand that the wind we feel on a windy day, the natural gas running through the line feeding a furnace and the propane that feeds a barbeque are also fluids.

FLUID FLOW How does fluid flow relate to our world? There are many examples of how fluid flow affects many people in many jobs. Engineers need to design building to withstand strong winds, if a heart has plaque build-up on artery walls and the blood is not able to flow the heart is considered unhealthy and, the design of an airplane is based on air flow.

FLOW RATE How quickly a fluid flows in a given amount of time. Systems involving moving fluids are said to be dynamic. Aerodynamic: Air (gas) moving around solid objects. Hydrodynamic: The movement of liquids around solid objects.

FLOW AND THE PARTICLE THEORY The Particle Theory States: - all matter is composed of particles - particles are in constant motion - there are forces of attraction among particles SOLIDS: - particles are very close together - force of attraction is strong - particles cannot flow past one another

LIQUIDS: -particles are moving rapidly -force of attraction are not strong -particles can slide past one another (flow) GASES: -particles are very far apart, further than a liquid -force of attraction is very weak -able to flow very easily

ASSIGNMENT Read pages 88 & 89 QUESTIONS 1-3 PAGE 89

ANSWERS 1) Using the particle theory, explain why solids do not flow. The particles in a solid are so close together and their forces of attraction are so strong that they cannot flow past one another. 2) How is the flow of air used in transportation? The flow of air which lifts an airplane. The aerodynamics of vehicles such as cars and trains to optimize speed and fuel efficiency. The manipulation of air in a hot air balloon… 3) Investigate how a water saving shower head works. These showerheads work by restricting the volume of water that they allow to flow through them. Newer models can reduce the volume of water used by half, but still provide an enjoyable showering experience! http://www.thegreenage.co.uk/tech/water-saving-showerheads/