Viscosity & Flow
What term describes a fluid's natural resistance to flowing smoothly?
Viscosity.
What is the scientific formula used to calculate density?
D = m/V
(Density = Mass divided by Volume)
Which type of fluid system uses compressed gases (like air) to do work?
A pneumatic system
What is the scientific definition of pressure?
The amount of force applied to a specific unit of area.
According to the Particle Theory of Matter, are the particles in a fluid ever completely still?
No, particles are always moving and vibrating.
If you heat up a liquid like molasses or honey, does its viscosity increase or decrease?
It decreases (it becomes thinner and flows faster).
If an object's density is greater than the density of the fluid it is placed in, will it sink or float?
It will sink
Which type of fluid system uses confined liquids (like hydraulic fluid or oil) to transmit force?
A hydraulic system
What is the mathematical formula used to calculate pressure?
(Pressure = Force divided by Area)
Why can liquids and gases easily flow and take the shape of their container, while solids cannot?
The particles in liquids and gases have enough energy to slide past one another, whereas solid particles are locked in a fixed structure.
What is the formula used to calculate the flow rate of a fluid?
flow Rate = Volume / Time (e.g., Liters per second).
What do we call the upward force exerted by a fluid on any object placed in it?
Buoyant force (or Buoyancy)
What scientific law states that pressure applied to an enclosed fluid is transmitted equally in all directions?
Pascal's Principle
What is the standard SI unit of measurement used for pressure?
The Pascal (Pa) or Newtons per square meter
What happens to the volume of most fluids when they are heated up?
They expand (thermal expansion) because the particles move faster and push further apart.
Heating a liquid makes it flow faster. What happens to the viscosity of a gas when you heat it up?
Its viscosity increases (it gets thicker/slower because the warmer gas particles collide more often)
According to Archimedes' Principle, if a cruise ship weighs 50,000 tonnes, how much water must its hull displace to stay afloat?
Exactly 50,000 tonnes of water
What is the main job of a valve in a hydraulic or pneumatic system?
To control, direct, or stop the flow of the fluid, and to prevent it from flowing backward
As you dive deeper and deeper underwater in a lake or ocean, what happens to the fluid pressure around you?
It increases (because there is more weight of water pressing down on you from above).
Why are gases highly compressible while liquids are almost entirely incompressible?
Gas particles have massive amounts of empty space between them to be pushed into; liquid particles are already packed very tightly together.
Besides temperature, name two factors that can affect how fast a fluid flows.
Particle size/shape, attraction force between particles, or the size/smoothness of the container or pipe
What does it mean if a scuba diver has "neutral buoyancy"?
They don't sink or float; they hover perfectly in place because their overall density matches the density of the water
Why do your ears "pop" when you fly high in an airplane or drive up a steep mountain?
The outside atmospheric pressure drops as you go higher, creating an unequal pressure balance with the air trapped inside your ears
If you apply a force of 20N to an area of 2m², what is the resulting pressure?
10PA
Using particle theory, explain why a hot air balloon is able to lift off the ground.
Heating the air inside the balloon makes the particles move faster and spread out. This makes the hot air less dense than the cooler air outside, causing the balloon to float upward.