Practice Unit Test Flashcards
- Which of the following statements is not a part of the Particle Theory of Matter?
A) Particles are always in motion
B) Particles of a solid are spread far apart
C) There are spaces between particles
D) Particles attract each other
➡️ Answer: B) Particles of a solid are spread far apart
- Which state of matter is the most compressible?
A) Solid
B) Liquid
C) Gas
D) Plasma
Gas
Define density and give the word equation for calculating it.
Answer: Density is the amount of mass in a given volume.
Equation: Density = Mass / Volume
. Why is density considered a characteristic property?
Answer: Because it stays the same for a given substance, no matter the size of the sample. It can be used to identify unknown materials.
Explain what happens to the particles in a gas when the temperature is increased.
➡️ Answer: They move faster, spread out more, and collide more often, increasing pressure if contained.
Use the particle theory to explain why honey flows faster when heated.
➡️ Answer: Heating gives particles more energy to move faster and slide past each other, reducing viscosity.
- A submarine controls its depth by changing the amount of water in its ballast tanks.
a) Explain how this changes the average density of the submarine.
b) How is this related to buoyant force?
a) Taking in water increases mass, raising the average density so it sinks.
b) When the average density is greater than the water, the buoyant force is less than the weight, so the sub sinks.
- A craisin starts to rise and sink in a carbonated drink. What causes this movement? How does this relate to density and buoyancy?
➡️ Answer: Bubbles stick to the craisin, increasing volume and lowering average density → it floats. Bubbles pop → density increases → it sinks.
- Define viscosity and explain how it is measured in a lab setting.
➡️ Answer: Viscosity is a fluid’s resistance to flow.
It’s measured using a flow rate test (time it takes for a fluid to flow a distance or drop through a tube).
- How does the viscosity of a gas change with temperature? How does that compare to a liquid?
Gas: Viscosity increases with temperature.
Liquid: Viscosity decreases with temperature.
- Which system uses incompressible fluids to transfer force?
A) Pneumatic
B) Hydraulic
C) Mechanical
D) Electrical
Hydraulic
- In a simple hydraulic system, if you apply force to a small piston, what happens at the larger piston?
➡️ Answer: The pressure is transferred equally, but the larger piston experiences greater force due to its larger area (Pascal’s Principle).
- Compare the human circulatory system to a hydraulic system in terms of components and function.
Component Human Body Hydraulic System
Pump Heart Hydraulic pump
Fluid Blood Oil/water
Tubing Blood vessels Pipes/tubing
- Explain why pneumatic systems are better suited for devices like air brakes or dentist tools, while hydraulic systems are used for lifting heavy objects.
Pneumatics use air, are lighter, and can be faster and safer for small tools.
Hydraulics use incompressible liquids, allowing precise and powerful lifting of heavy loads.
Which statement best describes why gases are compressible and liquids are not?
A) Gases are heavier than liquids
B) Gas particles are farther apart and can be pushed closer together
C) Liquids don’t have mass
D) Gases are denser than liquids
➡️ Answer: B) Gas particles are farther apart and can be pushed closer together
How does the Kinetic Molecular Theory explain why a balloon expands when heated?
➡️ Answer: When heated, the gas particles inside the balloon move faster, hit the walls more often with more force, and spread out, causing the balloon to expand.
Which of the following best describes what happens in a hydraulic system?
A) Gas is compressed to store energy
B) Liquid transfers pressure to move objects
C) Air creates a vacuum
D) Pressure is created by friction
➡️ Answer: B) Liquid transfers pressure to move objects
Why do solids generally have a higher density than gases?
➡️ Answer: In solids, particles are packed tightly together, so there is more mass in a smaller volume compared to gases, where particles are far apart.
Why is air used in pneumatic systems instead of liquids?
➡️ Answer: Air is compressible, easy to store and release quickly, making it ideal for tasks that require speed and flexibility (like dentist tools or paint sprayers).
