Science 7/8

Fluids

Introduction to the Unit

The study of fluids, which can be either liquids or gases, introduces students to fluid mechanics, an area of knowledge important in many industries (such as aeronautics, engineering, meteorology, and oceanography). Fluids, including air and water, are essential to many industrial processes and form the basis of hydraulic and pneumatic devices. Students will learn about the properties of fluids by experimenting with and investigating the viscosity and density of different liquids and ways in which these properties affect objects placed in those liquids. Students will explore the implications of Archimedes’ Principle by investigating and measuring the buoyant forces on different objects. As well, they will learn about the diverse applications of the principles involved in fluid mechanics, including industrial applications such as jet propulsion, and everyday applications such as ensuring that sauces are cooked to the right consistency (degree of viscosity).

Remember:

A Fluid is a state of matter, such as liquid or gas, in which the component particles (generally molecules) can move past one another. Fluids flow easily and conform to the shape of their containers. Solids are not considered to be fluids because their molecules cannot move past one another and thus they have a definite shape.

Viscosity refers to the resistance of a substance to flow. For example, water has a lower viscosity than molasses and flows more easily.

Flow Rate is the the amount of fluid that flows in a given time across a given distance. Flow rate provides a measurement to determine how viscous (thick or thin) a fluid is. The viscosity (and thus flow rate) of a fluid can be altered by temperature.

For a humorous (although informative) aid in distinquishing between fluids and non-fluids watch the following clip:

Finally, the final clip provides a good example of how viscosity can alter flow rate. Don't try this at home, but if you do...video it! ha

We will be doing a lab report on this topic in an upcoming class:

INDENTIFYING COMMON FLUIDS AND THE PARTICLE THEORY

Complete the following two activity pages:

Introduction to Fluids

CHANGES OF STATE

Reminders:

Change of State - The transformation of a substances physical state into another state.

Melting - The process of changing from a solid to a liquid.

Vaporization - The process of changing from a liquid to gas.

Condensation - The process of changing from a gas to a liquid.

Freezing - The process of changing from a liquid to a solid.

Sublimation - The process of changing from a solid to a gas without going through the liquid state.

Experiment to try at home! (sorry parents)

https://www.instructables.com/id/How-To-Make-Magic-Mud-From-a-Potato/

HOW FAST DO FLUIDS FLOW? (Day 3-5)

Science Lab Report # 1

Some fluids flow faster than others. While orange juice flows freely, honey or syrup pours at a slower rate. In order to compare the speed at which fluids flow we will measure the flow rate of various liquids in our first science lab.

Flow Rate - The time it takes for a fluid to flow from one point to another. It is a good indicator of viscosity.

To calculate flow rate you need to measure the time (in seconds) that it takes for a certain amount of a fluid to travel a specific distance (in centimeters).

Ok your turn to try it out if you can! Conduct your own science experiment called "Measuring the Flow Rate of Liquids." See Google Docs for your lab report guideline and rubric.

The following clip shows a close proximity to the lab that you will conduct at home comparing the various liquids, their viscosities and their flow rates.

WHY VISCOSITY VARIES (Apr 14-17)

Factors That Affect Flow Rate

(1) Temperature has an affect on flow rate. In most cases, the hotter the temperature the higher the flow rate, while the colder the temperature the slower the flow rate.

(2) Fluids have different viscosities and size of the particles (bulkiness).

(3) Internal friction (rubbing) of particles as they slip past each other also varies between liquids.

Watch the short video on "The Boston Molasses Disaster of 1919." This documentary (created by the History Channel - Biggest Disasters of the 20th Century) not only describes the tragic impact that temperature can have on fluids, but more importantly demonstrates the need for humans to not cut corner when constructing tanks that hold large quantities of certain fluids.

LAB: Temperature and Viscosity See Notes - Due Friday April 17)

BIG IDEA 1: As temperature increases, the viscosity of a fluid decreases. When temperature increases, the particles move faster and the space between the particles increases. Because the space between the particles increase and the movement of the particles get faster, the attraction between the particles decrease. As a result of the decreased attraction between the particles, the viscosity decreases. On on contrary, as the temperature decreases, the viscosity increases because the particles move slower, space between particles decrease, and attraction between particles increase.

BIG IDEA 2: When you increase the temperature of a fluid, it affects the viscosity, but it does NOT affect the mass. The mass of the room temperature corn syrup and the heated corn syrup remains the same because the number of particles in the test tube did NOT change as a result of heating. The only thing that changed with adding heat is it caused the particles to move faster and further away from each other. This would result in a slight increase in volume, but mass remains the SAME.

VIDEO CLIPS OF VISCOSITY LABS AND DEMONSTRATIONS:

Watch the video clips below to review viscosity. The video talks about bonding between molecules in fluids. Don't worry too much about that. Just think about how molecules are attracted to each other (particle theory) and how that attraction affects viscosity.

Example

Here is an example on the effects temperature has on viscosity using shampoo

Example

Here is an example on the effects temperature has on viscosity using honey

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