Fluids
Learn about the properties of fluids.
This workshop consists of various experiments to explore the viscosity and density of different fluids.
What You Need
Physical Requirements
- A computer and projector for the presentation (optional).
Density Tower
- Small, transparent cup or bottle
- Water
- Corn syrup
- Cooking oil
- Dish soap
Cornstarch and water
- Corn starch (1/2 cup per student)
- Bowl
- Water
- Craft stick or spoon
Viscosity race
- Different types of liquids (cooking oil, water, corn syrup, dish soap)
- Foam board, 11" x 6" or a baking sheet
- Table cloth to catch drips (or paper towel)
Milk and Food Colouring
- Milk, 40-50ml (homogenized is best)
- Bowl
- Dish soap
- Q-tip
- Food colouring
Activity Guide:
Presentation:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual delivery to youth.
What To Do
Introduction
Use the presentation to discuss the following topics:
- The particle theory of matter.
- Density (mass/volume).
- If you have three balls of the same volume, made out of aluminum, wood and cork respectively, which one is the most dense?
- The properties of solids, liquids and gases.
Density Tower
- Hand out containers of water, corn syrup, cooking oil and dish soap, along with a clear cup to each student.
- Tell students to predict which fluid will be the most dense. They will slowly pour this liquid into the cup first.
- Have students continue to pour the rest of the liquids into the cup.
- Ask students to share their observations with the group. Did they predict correctly which liquid would be the most and least dense?
Cornstarch and Water
- Hand each student a bowl with 1/2 cup of cornstarch and stir stick.
- Have students slowly add water to the cornstarch, a little bit at a time.
- Let students explore the mixture. When pressure is added, it should behave like a solid. In the absence of pressure, it should flow like a liquid (non-Newtonian Fluid).
Viscosity Race
- Discuss viscosity (how fast or how slow a fluid flows).
- Hand out containers of water, corn syrup, cooking oil and dish soap, along with a piece of foam board or baking sheet to each student.
- Have the students predict which fluid/liquid will be the most viscous.
- Have students hold their foam board or baking sheet at an angle and add a bit of each liquid to the top of the sheet. The race is on!
- Ask students to share their observations. Which liquid was the most viscous? The least viscous?
Milk and Food Colouring
- Hand out a bowl of milk, food colouring, dish soap and a Q-tip to each student.
- The students can add a few drops of food colouring to their bowl of milk.
- Have students dip the Q-tip into the dish soap, then into their bowl of milk.
- Ask students to share their observations. What happened?
Discovery
Particle Theory of Matter states that,
- All matter is made up of tiny particles.
- All particles are in constant motion.
- Particles in solids and liquids are close together whereas in gases they are further apart with large spaces between them.
- Temperature affects the speed of particles.
- All particles of one substance are identical.
- Particles attract each other.
Density is a physical property of a fluid. It is the measurement of mass/volume. If you have two liquids of the same volume, the heavier one will be the more dense one. For example, corn syrup is denser than cooking oil.
Viscosity is another physical property of a fluid. It describes how fast or slow a liquid flows. The speed that a liquid flows has to do with shearing or the force of friction of the molecules/particles in the liquid moving past each other. Some liquids have stronger forces that hold the particles/molecules together called intramolecular forces that affect viscosity. The harder it is for a liquid to move, the more viscous the liquid and the more friction the liquid has internally. For example, corn syrup is more viscous than cooking oil.
Non-Newtonian fluids do not behave as one state of matter. In the case of the cornstarch and water mixture, the cornstarch particles are only suspended in the water, not dissolved. When a force is applied to the mixture, the cornstarch particles get mashed together and it behaves like a solid. When there is no force, the mixture flows like a fluid.
Milk and Food Colouring
In this experiment, the fluids are repelling each other. The negative end of the soap molecules line up with the positive end of the water molecules in the milk causing the spread of the food colouring. The negative charge on the soap molecules is also attracted to the positive part of the proteins in the milk and the uncharged part of the soap molecules line up with the uncharged fat in the milk, which causes all sorts of swirling.
Properties of fluids like viscosity and density are used in many aspects of everyday life, such as baking, hydraulics, deciding what car oil to use in cold climates, etc.
Hydraulic systems utilize the large amount of power that is generated when pressure is put on a small amount of fluid to life heavy objects. The brakes on cars, wheelchair lifts and some fair rides use hydraulic suspensions. Our circulatory system is another example of a hydraulic system- our heart provides the hydraulic pump to keep the blood flowing through our bodies.
Explore the density and viscosity of other fluids found around your house! Which is more dense: ketchup, honey or mustard?
What's Happening?
Particle Theory of Matter states that,
- All matter is made up of tiny particles.
- All particles are in constant motion.
- Particles in solids and liquids are close together whereas in gases they are further apart with large spaces between them.
- Temperature affects the speed of particles.
- All particles of one substance are identical.
- Particles attract each other.
Density is a physical property of a fluid. It is the measurement of mass/volume. If you have two liquids of the same volume, the heavier one will be the more dense one. For example, corn syrup is denser than cooking oil.
Viscosity is another physical property of a fluid. It describes how fast or slow a liquid flows. The speed that a liquid flows has to do with shearing or the force of friction of the molecules/particles in the liquid moving past each other. Some liquids have stronger forces that hold the particles/molecules together called intramolecular forces that affect viscosity. The harder it is for a liquid to move, the more viscous the liquid and the more friction the liquid has internally. For example, corn syrup is more viscous than cooking oil.
Non-Newtonian fluids do not behave as one state of matter. In the case of the cornstarch and water mixture, the cornstarch particles are only suspended in the water, not dissolved. When a force is applied to the mixture, the cornstarch particles get mashed together and it behaves like a solid. When there is no force, the mixture flows like a fluid.
Milk and Food Colouring
In this experiment, the fluids are repelling each other. The negative end of the soap molecules line up with the positive end of the water molecules in the milk causing the spread of the food colouring. The negative charge on the soap molecules is also attracted to the positive part of the proteins in the milk and the uncharged part of the soap molecules line up with the uncharged fat in the milk, which causes all sorts of swirling.
Why Does It Matter?
Properties of fluids like viscosity and density are used in many aspects of everyday life, such as baking, hydraulics, deciding what car oil to use in cold climates, etc.
Hydraulic systems utilize the large amount of power that is generated when pressure is put on a small amount of fluid to life heavy objects. The brakes on cars, wheelchair lifts and some fair rides use hydraulic suspensions. Our circulatory system is another example of a hydraulic system- our heart provides the hydraulic pump to keep the blood flowing through our bodies.
Investigate Further
Explore the density and viscosity of other fluids found around your house! Which is more dense: ketchup, honey or mustard?