Fluids, Density, and Particle Theory

Flashcards based on lecture notes about fluids, density, and related concepts.

What is density and how is it calculated?

Density is how tightly and heavily packed the molecules are in an object. It's calculated by mass / volume.

What is particle theory?

1. All matter is made of tiny particles. 2. Particles are in constant motion. 3. Particles never touch each other. 4. Particles attract. 5. When heated, particles move faster.

What is a fluid? Give an example.

A fluid is a substance that doesn’t have a definite shape, flows, and takes the shape of its container. An example is Oxygen.

What is Archimedes' Principle? Why is it important?

The buoyant force is equal to the weight of the displaced water. Important for engineers designing things like ships.

What states of matter are considered fluids?

Liquids and gases.

What are the characteristics of a fluid?

A substance that doesn’t have a definite shape, flows, and takes the shape of its container.

What is adhesion and cohesion?

Adhesion is the attraction between particles of a fluid and another substance. Cohesion is how strongly fluid particles are attracted to each other.

What is the difference between laminar and turbulent flow?

Laminar flow is smooth and streamlined, while turbulent flow is irregular and chaotic.

What is buoyancy? Where is Buoyancy applied?

An object’s tendency to float. Applied to any object that is fully or semi-submerged in a fluid.

What is the difference between a hydraulic system and a pneumatic system? Give examples of each.

A hydraulic system is powered by liquid pressure. A pneumatic system is powered by gas pressure.

What is surface tension?

The tendency of a liquid to resist an external force and minimize its area, due to the cohesive nature of particles.

What is viscosity? What factors affect it? How do they affect it?

A fluid’s resistance to flow. Affected by friction, cohesion, adhesion, temperature, concentration, and particle size. Increased temperature reduces the viscosity of a liquid.

What is the difference between mass, weight, and volume?

Mass is the amount of matter in an object. Weight is the amount of gravity acting on an object. Volume is the amount of room something takes up.

What are some bodily fluids?

Blood, sweat, and oxygen.

How would you determine if an object will sink or float in a fluid?

By calculating the object's density and the fluid’s density. The object will float if its density is lower; it will sink if its density is higher.

What effects does temperature have on the viscosity of a Liquid? How does this compare to the effects it has on a gas?

Increased temperature reduces the viscosity of a liquid, while it increases the viscosity of a gas.

What is a flow rate?

A term used to measure how quickly a fluid will move.

What objects have high density? What objects have low density?

High density: bowling balls, steel, brick, and stone. Low density: volleyballs, basketballs, sponges, and corks.

How do boats float in the water?

Ship engineers make sure that the insides of the ship are mostly hollow, so it weighs less than the displaced water below.

How do hot air balloons fly? How do they go down?

Hot air balloons fly by heating the air inside the balloon, reducing its density. They descend by stopping heating the air, increasing its density until it equals the outside air.

How do airships fly? How do they go down?

Airships fly by pumping helium into the balloon, making it less dense than the surrounding air. They descend by pumping air into the balloon, making it negatively buoyant.