The STEM ConnectionLesson 8 Big Idea

There is a significant relationship between science, technology, engineering, and mathematics.

Purpose of Lesson: To apply scientific knowledge to a thermal control system.

Lesson 8: The STEM Connection

Lesson 8 Big Idea

There is a significant relationship between science, technology, engineering, and mathematics.

Engagement – Students will observe and record what they see when a bimetallic coil is placed on the overhead projector and allowed to warm. Students will speculate what the coil is and what is happening to it.

Purpose of Lesson: To apply scientific knowledge to a thermal control system.

9/30 Drill

• Observe the demonstration and write what you saw happen.

Engagement

Exploration

• We will measure the range of the coil by heating and cooling it to some known temperatures.

• The data will be graphed and later used to determine its position at a desired temperature.

Collect 3 pair of data and graph.

Temperature Angle

32 degrees F 82

75 degrees F 90

380 degrees F 116

Temp. Deg. F

Ang

le

• Crawlspace vent

Explanation

Bimetals

• A bimetallic strip consists of two metals that expand at different rates. The difference in expansion causes the metal to bend.

Metals expand when heated.• How could that help us here?

The Blackbird's extraordinary performance demanded extraordinary technology. Titanium alloy skin was necessary to resist the 600-degree temperatures caused by air friction at Mach 3.

• Skin panels had to have moveable joints to accommodate expansion and contraction with temperature changes. (The Blackbird literally grew several inches at Mach 3.) As a result, the SR-71 constantly leaked fuel on the ground. This necessitated a special heat-resistant non-volatile fuel called JP-7, used in no other aircraft.

Let’s explore the thermal properties of some materials.

2/10 Copy

• Heat Treating Materials–Annealing - heating a material then

letting it cool gradually will soften it, make flexible.

–Tempering – heating a material then cooling it rapidly will harden it, make brittle

2/11 Rules and Limits

• Criteria- A desired specification of a product. A rule concerning the outcome. –Ex. The fan must turn on at 130 degrees F

• Constraint – A limit to the design process. –Ex. The system must fit within the roof

space

• Modeling, testing, evaluating, and modifying are used to transform ideas into practical solutions.

Modeling

Modifying Evaluating

Testing

The cycle ends when the products satisfies all of the goals related to the criteria.

6/6 Drill Copy the Graphic Below

6/2 Drill

• Identify some other devices (systems) that may use a cooling system similar to our model–Car engine–Laptop computer–Greenhouse