Characteristics of Fluids

Characteristics of Fluids
• Fluids have certain characteristics that define them as fluids
• Ex. Fluids do not have a definite shape of their own – both fluids and gases take the shape of their containers
• Liquids do have a definite volume

Continued
• Gases – completely fill any empty container they are placed in
• Ex. What would happen if a scared skunk got trapped in our school?

The Particle Theory of Matter
• The particle theory helps explain why fluids act the way they do
• It states:
– All matter is made of tiny particles
– Particles are moving randomly all the time
– Particles move faster and spread farther apart when they are heated up
– Particles attract each other

Solids
• Solids have a definite shape and volume
• The particles in a solid are always in motion, but the forces of attraction are so strong that the particles vibrate very small distances around a centre point
• Solids are generally not fluids because the particles cannot slide past each other

• Draw the particles in a solid below:

Liquids
• Particles in a liquid are farther apart than in solids • They are bound less tightly and are free to move past one another
• The forces of attraction among particles in a liquid are still strong enough to hold the liquid together

• Draw the particles in a liquid below:

Gases
• The particles in a gas are much farther apart, and their force of attraction is extremely small • Gas particles spread out and fill whatever container they are placed in

• Draw the particles in a gas below:

Ability to Flow
• Fluids have the ability to flow because the particles of liquids and gases are free to mve about • A characteristic of fluids is that they can flow through, around or over something Ability to Flow
• Some solids can appear to flow (ex. Salt, sugar, sand), especially when they are ground into very fine fragments • If you look closely at each particle of salt, sugar, or sand, each fragment still has a definite shape
• Solids form piles when poured, fluids do not

Ability to flow
• Some solids – such as the ice in glaciers- are considered fluids
• The solids will exhibit fluid like behaviour when subjected to strong forces over long periods of time
• Ex. Glaciers moving
• Fluid solids are very uncommon in everyday life on Earth’s surface

Types of Flow – Laminar Flow
• Laminar flow is when fluids move in orderly lines or along smooth pathways
• Ex. In pipes and hoses
• For objects such as cars, boats and planes that move through fluids, laminar flow along the vehicle reduces resistance, or drag
• This makes the vehicle more efficient

Types of