Unit 29 - Non-Newtonian Fluids? (Fluids and its viscosity)

Non-Newtonian Fluids? (Fluids and their viscosity)

• One of the states of matter: liquids
• One of the property of liquids: viscosity 
• To recognize Newtonian Fluids from Non-Newtonian Fluids

A fluid is one of the three states of matter, the other two are solids and gases. In a nutshell, the characteristics of a solid are that they have a defined shape and volume, a liquid has a defined volume, but it takes the shape of the container and a gas has neither defined volume nor a defined shape.There are two types of fluids: the newtonian fluids, and the non-newtonian fluids. The first ones have the specific characteristic of keeping its viscosity constant in specific ranges of temperature and pressure, changing just when temperature and pressure are out of these ranges. Some examples of newtonian fluids are: water, juices, coffee, alcohol, milk, etc. In the case of non-newtonian fluids, viscosity changes under an applied force, making it behave more like a solid in some cases or more like a liquid in some others. Some examples of non-newtonian fluids are: ketchup, mayonnaise, tooth-paste, honey, shampoo and Oobleck.Notes: Remember that viscosity is defined as a measure of a fluid’s resistance to flow.  Notes:  Remember that viscosity is defined as a measure of a fluid’s resistance to flow. 

1. One day previous to the activity, ask the students to calculate the volume that the bucket must have if they want both of the feet of the classroom to fit in, with the condition that the minimum height of it should be 15 cm. 
2. Once calculated that volume, let the students know that is the quantity of water they will need, and twice of that quantity is the kg of starch that they will use.
3. During the day of the activity, with the calculations they’ve made, the students must prepare the cornstarch-water mixture (Oobleck) in each of the buckets. Students can let their creativity take the lead by mixing in the Oobleck their color and glitter of choice. 

In this game, students must make two teams (or maybe three teams, depending on the number of students you have), and play relays. The objective is to try to run in the place on top of the Oobleck without getting deep into it, they must maintain themselves running all the time to avoid sinking into the Oobleck. If students get tired of running, they can ask another student of their team to take their place, with the condition that all of the students have to participate at least once. The team that holds themselves for longer on the surface of the Oobleck, would be the winning team! The students can record themselves during the relays and make a small video about their experiences and what they’ve learned.  Be careful, running over Oobleck requires a lot of stamina! Enjoy the challenge! 

1. Ask the students if they could do that over another liquid, such as water, or salted water maybe. Discuss the answers. Maybe they would like to try.
2. Now you can introduce to the students the concepts of the states of matter; solid, liquid and gases, emphasizing on liquids and how they have two categories; newtonian fluids and non-newtonian fluids.
3. Bring some examples of other non-newtonian fluids so they can compare with the experience they just had.

1. Discuss about viscosity and how it maintains constant in newtonian fluids except when conditions such as temperature and pressure change, leading to a change in its matter state. Example: Water turns into Ice when its temperature lowers to  0°C and it turns into gas when it is 100°C.
2. Discuss about the properties (viscosity, velocity of the fluid) that change in non-newtonian fluids due to applied stress.

• Science - Making the Oobleck and understanding about Non-Newtonian Fluids
• Technology - Using apps to record their experience and an explanation of how they prepared the Oobleck and why it behaves like it does. 
• Engineering - Solving the problem of the Oobleck container (proportion wise and money wise)
• Physical Education - Running in a standing still race
• Art - Choosing the design of your Oobleck
• Mathematics - Finding the correct quantity of cornstarch and water to prepare the Oobleck..