Learning Activity 1: Newton and Flight
Students should have some prior knowledge of forces and motion. This activity can be followed by more detailed explanation of lift, drag, and other forces relating to flight.
1. Ask students if they have heard of Newton’s Laws of Motion. Explain, or ask a student to explain, that the Laws, first recorded by Sir Isaac Newton in the 17th century, are scientific guidelines that explain how forces and motions work for many physical objects and systems. Summarize the first two laws for students (you may write these on the board, project them on a screen, and/or ask students to write them in their notebooks for reference.)
- First Law: The “Law of Inertia.” A body at rest will stay at rest/a body in motion will stay in motion with the same speed and direction, unless acted on by an unbalanced force.
- Second Law: Force = mass x acceleration. The greater the object, the greater the force needed to accelerate the object.
2. Tell students that they may have heard of the Third Law before: For every action, there is an equal and opposite reaction. Write or project this Law along with the other two. Ask students what they think that means, in their own words. Explain, if students do not offer this answer, that there is no such thing as a force that only acts on one body. If body A exerts a force in one direction on body B, B will be exerting the same force on A. If you push against the wall, it may feel like you are exerting all of the force – but in actuality the wall is pushing back on you just as hard!
3. Explain to students that the Third Law of Motion is instrumental in explaining how flight works. Define flight for students as the process by which an object moves through the air by generating lift. Define lift as a mechanical force generated by a solid object moving through a fluid (usually a gas such as air). Lift is generated when a moving flow of fluid is turned by a solid object. Ask students how they think this relates back to Newton’s Third Law? (When the solid object exerts force on the moving flow of fluid, the flow exerts force on the solid object, pushing it in the opposite direction – in the case of flight, that direction can be up or forward.) Explain that the force counter to lift is called drag, which acts in the opposite direction of the motion of an object.
4. Direct students to the “Getting Airborne” interactive and tell them they will be learning about how wings create lift. Ask students to go through both parts of the interactive and identify how wing shape and position affects lift and flight. Distribute the “Flight Patterns” organizer for students to record their answers. Give students 10 minutes to complete the interactive. As a follow up question, ask students to imagine they are building a commercial passenger airplane. What kind of airfoil would they use on the plane, and why?
5. Ask students to think of examples of other flying things that generate their own lift. (Accept all answers that fit, be sure to make the distinction between actual flying things and gliding things such as flying squirrels.) Examples can include birds, insects, helicopters, rockets, etc. Explain that while the flight fundamentals are the same for all of these – generation of lift, drag, etc. – the specific mechanisms and types of flight vary. Tell students that you are going to show them an example of a unique type of flight found in nature – the hummingbird. Ask students to observe, as they watch the video clip, how hummingbird wings generate lift. Play “Hummingbird Flight” clip. Give students five minutes to complete side 2 of the “Flight Patterns” organizer. Replay clip if necessary.
6. Ask students if they noticed any big differences between hummingbird flight and that of other birds, or airplanes. (Hovering, flying backwards.) As a homework assignment (which students may begin in class, if time permits), have students research and write a one-page summary of how hovering works. Ask students to address the following questions in their summaries:
- How does hovering differ from traditional bird flight?
- How do lift and drag factor into hovering flight?
- Is wing shape relevant to the ability to hover?
Learning Activity 2: The Heat is On
This activity can be used as an introduction to a unit on thermodynamics and heat transfer. Students should already be familiar with concepts of energy and mechanical work.
1. Begin by defining thermodynamics as the physics of relationships between heat and other forms of energy. Explain the study of thermodynamics includes the effects of heat on various states of matter, and the ways in which heat is related to other forms of energy. Explain there are scientific laws that apply to thermodynamics, just as Newton’s Laws apply to motion. Tell students in this activity, they will be focusing on the First Law of Thermodynamics, which states energy can neither be created nor destroyed in the conversion of heat to or from other forms of energy. Any energy put into a system must be used in some capacity, such as changing internal energy (generate heat) or performing work.
2. Explain to students much of thermodynamics related to the changes in energy within a thermodynamic system. There are three types of thermodynamic systems: isolated, in which no energy or matter is exchanged with the system’s surroundings; closed, in which energy is exchanged but not matter; and open, in which both energy and matter are exchanged. These changes in energy, which can result from changes in pressure, volume, internal energy, temperature, or any other kind of heat transfer, are known as thermodynamic processes. Review with students four common types of thermodynamic processes:
- Adiabatic: internal energy remains constant; no heat transfer into or out of the system.
- Isochoric: the volume of the system remains constant; the system does no work
- Isobaric: the pressure of the system remains constant; volume expands or contracts based on heat transfer
- Isothermal: temperature of the system remains constant; heat transfer occurs at a slow rate to preserve equilibrium.
3. Divide students into pairs, or have them work individually, depending on availability of materials. Distribute one hand boiler to each student or pair of students, and give each student one “The Heat is On” organizer. Have students answer the first question on the organizer: What kind of thermodynamic system is the hand boiler: isolated, closed, or open? (Closed.) Discuss why this answer is correct with the class. (No matter can be put into or taken out of the boiler, but the conductive glass allows for energy transfer into the boiler.) Have students follow the instructions on the organizer to achieve different results with the hand boilers. Give students 10 – 15 minutes to complete the activity.
4. Tell students that you are going to show them a video clip of how conservation of energy and thermodynamic processes work in nature. Ask students to identify the thermodynamic process(es) at work as they watch the clip, and to record their observations on the “The Heat is On” organizer. Play “The Heat is On” clip. After clip has finished, give students 5 minutes to complete the questions on the organizer. Replay clip if necessary. Review answers with class.
5. As a homework assignment (which students may begin in class, if time permits), ask students to research and write a one-page summary of another plant or animal that relies on the conservation of energy or thermodynamic processes for survival. Potential subjects include hibernating animals, animals that incubate eggs, or plants engaging in photosynthesis. Ask students to address the following questions in their summaries:
- What thermodynamic process(es) are at work in this plant or animal?
- How is energy being converted within this plant or animal?
Learning Activity 3: Making Waves
This activity can be used as an introduction to the properties of sound. Students should be familiar with basic properties of waves.
1. Ask students, based on either prior knowledge or their best guess, where sound comes from? (Vibrations.) How do vibrations cause sound? (Waves travel through a medium, and cause the individual molecules to vibrate.) Explain that sound waves have four principal characteristics, and write them on the board.
1. Wavelength: the distance between two equivalent points on a wave (such as crest to crest)
2. Period: the time required for one complete wave cycle to pass a given point, or travel one wavelength
3. Frequency: the number of wave cycles per second that are produced by a source. Wavelength and frequency are closely related, as longer wavelengths have lower frequencies, and shorter wavelengths have higher frequencies. The wavelength and frequency of a sound wave are related to the sound’s pitch: higher sounds have higher frequencies and shorter wavelengths.
4. Amplitude: the height of a wave, or the maximum disturbance from an undisturbed position. The amplitude of a sound wave corresponds to the sound’s volume: higher amplitudes make for louder sounds.
2. Specific sounds are created when objects vibrate at specific frequencies. Tell students that you are going to show them a video clip of a specific sound produced by the Anna’s Hummingbird. Ask students to observe, as they watch the clip, how the aforementioned properties of the sound waves contribute to the hummingbird’s unique sound. “Distribute the “Making Waves” organizer for students to record their observations. Play the “Making Waves” clip. Give students 5 – 10 minutes to complete Part 1 of the organizer. Review answers with the class. Ask students how they might be able to recreate the hummingbird “chirp” here in the classroom.
3. Tell students that they are now going to participate in a hands-on activity to create their own specialized sounds using different wavelengths, frequencies, and amplitudes. Give each student a regular drinking straw and a pair of scissors. (Have many extra drinking straws available as students may want or need more than one each.) Have students follow the instructions listed in Part 2 of the Making Waves organizer to create a basic reed instrument with the drinking straw. Give students 15 – 20 minutes to complete the activity. When they have finished, ask students to share their observations from the activity with the class.
4. As a homework assignment (which students may begin in class, if time permits), have students choose a more complex reed or woodwind instrument to research, and write a one-page explanation of how it creates its sound. Ask students to address the following questions in their explanations:
- How does your particular instrument create sounds with different frequencies or amplitudes?
- How does the instrument transmit its sound to listeners?
Learning Activity 4: The Light Fantastic
Students should already have a basic knowledge of the light spectrum and of waves. This activity can be used to enhance students’ understanding of the visible light spectrum.
1. Begin by telling students you are going to show them a video clip to introduce the light wave phenomenon known as iridescence. As they watch the video clip, ask students to observe the colors they see on the hummingbirds, and why they are present. Play “The Light Fantastic” clip for students. Review answers to the question asked before the clip was played (colors present were purple, red/ruby, orange, green, blue, and they are due to iridescence rather than pigment.) Ask students, based on the clip, to define characteristics of iridescence. (Change color in different light, not related to pigment, light is broken down into different wavelengths.)
2. Ask students if they can think of other organisms or objects that display properties of iridescence? (some butterflies, peacocks, beetles, pearls, oil slicks, CDs and DVDs, soap bubbles.) Why does this phenomenon occur? Explain that there are different characteristics of light waves that can contribute to iridescence:
1. Reflection, which is when a light wave hits a surface and bounces back toward its source, such as looking at yourself in a mirror
2. Refraction, which is when the direction of a wave changes due to a change in its speed. This is often due to a change in medium. If you look at a drinking straw in a glass of water, you’ll see that the straw’s angle appears to be different above the surface of the water than it is below the surface.
3. Diffraction, which is what happens to a wave when it encounters an obstacle, such as an obstruction, small opening, or inconsistencies within a medium. This is visible in the rainbow pattern we see on the back of a CD or DVD, as light passed over the tiny grooves in the disc’s surface.
4. Interference, which is when two or more waves combine to make a new wave. If the waves are in phase with each other, they are called constructive, and will reinforce and intensify. If the waves are not in phase, they are said to be destructive, and will cancel each other out. This is what provides the brilliant colors found on iridescent surfaces.
3. Tell students that they are going to conduct an activity to explore some of the characteristics of iridescence. Divide class into small groups or pairs, depending on the availability of material. Distribute one container or soap bubbles and a bubble wand to each group. Ask the students to blow bubbles, and observe the colors and patterns on the bubbles’ surfaces. Students should experiment with different sizes and thicknesses of the bubbles, and record their observations as on the “Light Fantastic” organizer. Give students 15 – 20 minutes to blow bubbles and complete the organizer. Review answers with the class.
4. Explain that the iridescent properties of the bubbles, like the brilliant colors of the hummingbird feathers, are caused by the light reflecting from the object’s surface. The thickness of the surface influences what type of light is reflected. In hummingbird feathers, the microscopic layered structure provides different surfaces and thicknesses to reflect light. In a soap bubble, the thickness of the soap film is constantly changing as the bubble takes shape. White light reflects off both the inner and outer surfaces of the bubble, at different angles. In both cases, the reflecting waves of light from the different surfaces interfere with each other. Depending on the thickness of the surface, certain wavelengths will interfere destructively and other wavelengths will interfere constructively, intensifying the color that corresponds with that wavelength. A thicker surface will cancel out longer wavelengths, such as those at the red end of the spectrum. As the surface gets thinner, shorter wavelengths will cancel each other out. This explains the changes in color as the soap bubbles grew thinner and eventually popped.
5. As a homework assignment (which students may being in class, if time permits), have students choose another iridescent object or organism (as listed earlier in this activity) to research, and write a one-page explanation of the properties and characteristics of that object that cause it to be iridescent. Ask students to address the following questions as part of their explanations:
- What material is present in their chosen object or organism that allows it to be iridescent?
- What particular colors or wavelengths, if any, are especially noticeable in this object or organism?
- How does this object or organism benefit from being iridescent?