Slide 1 Presentation 2: Introduction Duration: 00:00:16 Advance mode: Auto. Slide 2 Reading Assignment Duration: 00:00:24 Advance mode: Auto

Transcription

1 Slide 1 Presentation 2: Introduction Duration: 00:00:16 Advance mode: Auto Welcome to Presentation Two, Physical Science, in the Reviewing Science course. During this presentation, we will explore forces and motion, physical and chemical properties, energy and interactions, and energy transformations and conservation. Slide 2 Reading Assignment Duration: 00:00:24 Advance mode: Auto Before you begin viewing the presentation, it is important that you complete the reading assignment. The reading assignments are listed on the course checklist available on the Blackboard course documents page. The presentation expands on information from the reading, and in some cases, additional information is shared to best meet the state standards. The assessment at the end of the module will include information from the readings as well as the presentations.

2 Slide 3 Presentation 2: Forces and Motion Duration: 00:00:16 Advance mode: Auto In this section, we will explore Forces and Motion. To meet the objectives, the teacher must understand forces and motion and their relationships. This foundational knowledge will help prepare teachers to guide EC-6 students in their study of the physical sciences. Slide 4 The Properties of Universal Forces Duration: 00:03:09 All of the forces in the universe can be categorized into these broad groups: nuclear force, electromagnetic force, and gravitational force. We will focus on three universal forces: gravitational force; electrical force; and magnetic force. Forces can be attractive or repulsive. Attractive forces are pulling forces, and repulsive forces are pushing forces. Click the tabs to learn more. Gravitational force, or gravity, is the force of attraction that exists between all objects in the universe. The most familiar example of the gravitational force is your weight. Your weight is the force of attraction between you and the earth. The force of gravity is proportional to the product of the masses divided by the distance between them squared. The larger the mass, the larger the force due to gravity. The smaller the mass, the smaller the force of gravity. The opposite is true for the distance between them. The larger the distance between the objects, the smaller the gravitational force. The closer the objects are to one another, the greater the gravitational force. This is why you would weigh less on the moon. The moon is much less massive than the earth, so the attractive force between you and the moon is

3 less than the attractive force between you and the earth. The electric force is the force of attraction or repulsion between charged particles. If the charges are both positive or both negative, the force will be repulsive. If the charges are opposite, the force will be attractive. The most common example of the electrical force is the force that holds the elements together in all of the compound matter in the universe. Consider the crystals of sodium chloride, or table salt. Positive sodium ions are attracted to negative chlorine ions, and they hold together as solid crystals because of the electric force. The electrical force relation is similar to the gravitational force relation. The electrical force is proportional to the product of the charges divided by the distance between them squared. The greater the charge, the larger the force. The smaller the charge, the smaller the force. The opposite is true for the distance between the charges. The larger the distance, the smaller the force. The closer the objects, the greater the force. The magnetic force is the force of attraction or repulsion around magnets. A magnet is any object with two opposing poles that produces a magnetic field. The magnetic field effects magnets, charged particles, and substances containing iron, nickel, or cobalt. The strength of the force depends on the strength of the magnetic field and the distance between the magnet and the object. The force between magnets is attractive if the opposite poles are brought together and repulsive if the same poles are brought together. Examples of magnets include lodestone, magnetized iron bars, electromagnets created by an electric current flowing through a coiled wire, and the earth itself.

4 Slide 5 Force and Motion Duration: 00:04:47 Understanding force and motion leads to an understanding of why and how things move. It is the foundation for the study of physics, the study of matter and its motion. All matter in the universe is subject to the push and pull of forces. If the forces acting on an object are balanced, the object maintains its current state of motion. If the forces are unbalanced, the object initiates motion or changes its velocity or direction. Think about a tug of war game. If the students on opposite sides of the line are pulling with equal force, the rope will not move. If one team is pulling with greater force than the other team, the rope will move in the stronger team's direction. Proceed through each panel to apply your learning from the reading assignment and analyze the relationship between force and motion and how unbalanced forces can cause changes in the position or motion of an object. Balanced forces are equal in size and opposite in direction. Two balanced forces are acting on the ball. The force of gravity pulls the ball toward the center of the Earth, and the force of the surface pushes the ball up with an equal and opposite force. Balanced forces do not cause a change in motion. Unbalanced forces cause a change in motion because the forces are not equal and opposite. If the ball was pushed toward the left, the ball would move left unless there was an equal and opposing force. When a cat jumps off of a refrigerator, the force of the refrigerator is no longer pushing against the cat. As the cat falls, the force of gravity is pulling it down; only air friction is pushing against it. Since the force of air friction is much less than the force of gravity, the cat continues to fall until it makes contact with the floor. This set of unbalanced forces causes downward linear motion. When the cat lands, the floor pushes against the cat and stops its downward motion. When this box is sitting on the table, the force of gravity and the force of the table are equal and opposite. To unbalance the forces and lift the box, the girl will need to apply a force that is greater than the gravitational force acting on the box. If she can lift it, the unbalanced forces will cause an upward linear motion. Imagine a student is about to launch a small ball with a rubber band slingshot. At the moment before launch, the forces are in balance. The force of gravity on the ball is balanced by the force of the student's hand holding it up, and the

5 tension force of the rubber band on the ball is balanced by the force of the student's hand pulling the ball back. When the student lets go of the rubber band, the forces become unbalanced. Without the student's hand to pull the ball back and hold the ball up, the tension force pushes the ball forward and the gravitational force pulls the ball down. This combination of unbalanced forces causes projectile motion. Examples of force and motion are all around us. Students can investigate unbalanced forces on the playground. For example, a seesaw is a lever, one of six types of simple machines. Recall from the reading assignment that simple machines make work easier by changing the amount of force, the direction of force, or the distance over which force is applied. In the illustration, the force of gravity has a stronger pull on the boy than the girl. When the forces are balanced, the boy sits lower than the girl and holds her up. How can the girl use the seesaw lever to unbalance the forces and cause motion? If the girl moves forward, she can multiply the force of her weight and cause the boy to move upward. Examples of force and motion are in the classroom. Students can investigate unbalanced forces by building pulleys and other simple machines. For example, this wire hanger pulley is an example of a single-wheel pulley that makes work easier by changing the direction of the force. In the illustration, the force of gravity pulling on the suspended water jug is being balanced by the force of the girl pulling on the rope. How can the girl use the pulley to unbalance the forces and cause motion? If the girl lets go of the rope, the force of gravity on the water jug will pull the jug down. If the girl exerts a stronger pulling force, she can lift the water jug higher. Examples of force and motion are also in nature. Students can investigate unbalanced forces in nature by building models of natural processes. For example, this rock formation was created by water erosion millions of years ago. The force of flowing water over bedrock in rivers today is slowly creating the canyons of tomorrow. When the force of the water is unbalanced with the forces holding the rock together, tiny rock particles break off and are washed downstream.

6 Slide 6 Describing Changes in Motion Duration: 00:00:05 Slide 7 Presentation 2: Physical and Chemical Properties Duration: 00:00:18 Advance mode: Auto In this exercise, we will describe changes in motion. We'll start with a review of the vocabulary from the reading assignment. Review vocabulary from the reading assignment by choosing the best definition for each term. Position vs. time graphs describe the motion of an object relative to a stationary object (motion detector) at the graph's origin. The slope of the line indicates the speed and direction of motion. As the moving object travels away from the stationary object, the slope is positive. As the moving object travels toward the stationary object, the slope is negative. A fast-moving object has a steeper slope than a slow-moving object. Based on what you've learned, click on the arrow that indicates where the moving object changes direction. Which graph best illustrates the scenario described below? While standing at the bus stop, Joule notices his bus is down the street. He just missed it. Joule breaks into a jog toward the bus. As he s jogging, his keys fall out of his pocket, so he turns around and jogs back to get them. Joule stops to pick up his keys and catch his breath. Then he sprints toward the bus. Recall that acceleration is the change in velocity over time. Click on the graph that best illustrates acceleration. In this section, we will explore Physical and Chemical Properties. To meet the objectives, the teacher must understand the physical and chemical properties of and changes in matter. This foundational knowledge will help prepare teachers to guide EC-6 students in their study of the physical sciences.

7 Slide 8 Distinguishing Between Elements, Compounds, and Mixtures Duration: 00:00:05 In this exercise, we will learn how elements, compounds, and mixtures differ and describe their properties. We'll start with a review of the vocabulary from the reading assignment. Match the vocabulary word with the correct definition. A container holds a mixture of gases. Which picture below represents a compound in the mixture? A container holds a mixture of gases. Which picture below represents an atom in the mixture? Drag each description under the appropriate sample of matter. Slide 9 Physical and Chemical Properties Duration: 00:04:09 Matter can be described and identified by its unique physical and chemical properties. Physical properties are those characteristics that can be observed without changing the chemical identity of the substance. Chemical properties are characteristics that are observed during chemical reactions that change the substance's chemical identity. Click through the example properties to learn how we describe and measure the physical and chemical properties of matter. Size is the length, width, and/or height of an object. Size is a physical property of matter. It is measured most often in meters. Students can make quantitative observations about size using a ruler or a meter stick. Shape is a description of the form of an object. Shape is a physical property of matter. Students can make qualitative observations about shape by comparing objects to known shapes. An object's temperature indicates the average kinetic energy of the object's atoms. The higher the temperature, the more energy the atoms have. Temperature is a physical property of matter. Temperature is most often measured in degrees Celsius or Fahrenheit. Students can make quantitative observations about temperature with a thermometer. If a substance is magnetic, it will be attracted or repulsed by a magnetic field.

8 Magnetism is a physical property of matter. Students can make qualitative observations about magnetic properties by testing different substances with magnets. Hardness is a measure of how well solid objects can hold up to an applied force. Hardness is a physical property of matter. Hardness is most often tested on rocks and minerals. Students can make qualitative observations about hardness by testing different rocks and minerals with a fingernail, a penny, a knife, an iron nail, a piece of glass, and the Mohs hardness scale. Mass is the amount of matter in an object. Mass is a physical property of matter. It is measured most often in grams. Students can make qualitative and quantitative observations about mass using different types of balances. Conductivity describes a substance's ability to transfer electrons and conduct electricity. Conductivity is a physical property of matter. Substances that can conduct electricity are called conductors. Substances that cannot conduct electricity are called insulators. Students can make qualitative observations about conductivity by testing different substances with conductivity testers. Conductivity can be tested using a battery, a light bulb, and wires. If the substance is a conductor, it will complete the circuit and light the bulb. Density is the amount of matter contained in a certain volume. Density is a physical property of matter. It is measured most often in grams per milliliter. Students can make quantitative observations about density by measuring the mass and volume of an object and then calculating the density. Density = mass/volume. Volume is the amount of space an object takes up. Volume is a physical property of matter. It is measured most often in milliliters. Students can make quantitative observations about volume using different types of beakers and graduated cylinders. Some substances burn when they are exposed to heat. Flammability is a chemical property of matter. Students can make qualitative observations about flammability by safely observing a demonstration of whether some substances burn when exposed to heat. Some substances fizz when they come into contact with acids. Acid reactivity is a chemical property of matter. Students can make qualitative observations about acid reactivity by exposing different substances to drops of vinegar. Some substances turn brown or rust when they come into contact with oxygen. Oxidation is a chemical property of matter. Students can make qualitative observations about oxidation by testing whether different substances rust in

9 air. Slide 10 Describing Solid, Liquid, and Gas Properties Duration: 00:00:05 In this practice quiz, you will apply your learning from the reading assignment by describing the physical properties of solids, liquids, and gases. Drag each description to the appropriate phase of matter. Slide 11 Distinguishing Between Physical and Chemical Changes Duration: 00:00:05 Take this opportunity to practice distinguishing between physical and chemical changes. During the reading assignment, you learned that a physical change is a change in matter involving size, shape, or phase that does not produce a new substance. A chemical change is a change in matter involving the formation of a new substance with new properties. Chemical changes occur when the atoms of one or more substances are rearranged. In this exercise, select all that apply. Which of the following are examples of physical changes? Which of the following are examples of chemical changes?

10 Slide 12 Presentation 2: Energy and Interactions Duration: 00:00:17 Advance mode: Auto In this section, we will explore Energy and Interactions. To meet the objectives, the teacher must understand energy and interactions between matter and energy. This foundational knowledge will help prepare teachers to guide EC-6 students in their study of the physical sciences. Slide 13 Conservation of Energy Duration: 00:01:40 We often hear the phrase conserve energy as a helpful reminder. Conserving energy in nature is more than a reminder - it s the law! The law of conservation of energy states that energy cannot be created or destroyed but that all energy in the universe is constant. Though the total amount of energy is constant, its form is not. Energy can transform from one form to another. These two girls experience the transformation between potential and kinetic energy as they ride the roller coaster. The different forms of energy can be thought of as either kinetic or potential energy. Potential Energy is stored energy. The roller coaster cart at position 1 represents potential energy since the cart has the capacity move downhill due to its position. Oatmeal in a breakfast bowl can also be thought of having potential energy - chemical potential energy - to fuel your body. Kinetic Energy is the energy of motion. The faster the motion, the higher the kinetic energy. The roller coaster cart at position 2 represents kinetic energy since the cart is moving. Students swinging on swing sets can also experience the transformation between potential and kinetic energy. At the very highest point of their swing (before they change direction), they are momentarily motionless (zero kinetic energy) and possess the maximum

11 amount of potential energy. At the lowest point of their swing (before they move upward), they are moving the fastest and possess the maximum amount of kinetic energy and the least amount of potential energy. Slide 14 Types of Energy Overview Duration: 00:00:36 The different forms of energy were outlined in the reading assignment. Which form of energy could students investigate when experimenting with a tuning fork held over water? Slide 15 Electricity and Magnetism Duration: 00:01:52 Electrical energy, or electricity, is a type of kinetic energy resulting from the movement of electrons. Electrons move easily through conductors like this copper wire but not easily through insulators like glass or plastic. Static electricity forms when an object gains or loses electrons and becomes positively or negatively charged. When static electric charge builds up between objects, electricity can suddenly flow between the objects. Lightning is one example of this electrostatic discharge. Electricity can also flow continuously through conductive materials such as copper wire in an electric current. We apply the principles of electricity when we build circuits. Here is an example of an open circuit that students can build. As long as the circuit is open, electricity will not flow. Here is an example of a student-built closed circuit. Notice that the light bulb is lit, indicating that electricity is flowing. This circuit is also called a series circuit

12 because there is only one path for the flow of electricity. This circuit is also closed, but it is a parallel circuit. There is more than one path for the flow of electricity. Investigating simple circuits helps students understand how we use electrical energy to do work. A coiled wire on its own will not conduct electricity. However, if you move a magnet through the coil, it will produce an electric current. The converse is also true. If you run electricity through a coiled wire, you can produce a magnetic field. Slide 16 Light Duration: 00:01:00 Light is visible radiant energy. It s the only portion of the electromagnetic spectrum that human eyes can detect. Light has wave properties. When light waves hit a surface, the light will reflect, travel through the surface, be absorbed, or some combination of the three. When light waves travel through different materials (air, water, or glass), the light bends, or refracts, when the waves speed up or slow down. Students studying a pencil in a glass of water can investigate this effect. When light hits a mirror, it reflects off of the mirror at the same angle at which it hits it. Students can investigate this effect with a flashlight and a mirror. Students can use their knowledge to describe how different optical systems work. What property of light is being used in this periscope? If you said reflection, you are right!

13 Slide 17 Sound Duration: 00:01:21 Slide 18 Heat Duration: 00:00:32 Sound is a type of mechanical energy. When matter vibrates, it creates sound. Sound transmits its energy by passing along the vibration through other matter. This creates a sound wave. Since there is no matter between the stars and planets in outer space, there is no sound in outer space. Sound waves have wave properties. The pitch of the sound (high or low) depends upon the frequency (or number of waves per second) of the wave. High frequency sound waves appear compressed and sound high pitched. Low frequency sound waves appear spread out and sound low pitched. The volume of the sound (loud or soft) depends on the amplitude (or height) of the wave. High-amplitude sound waves appear tall and can create more vibrations and sound. Solid matter transmits sound better than liquids, which transmit sound better than air. In the movies, you sometimes see people putting their ear to the train tracks to hear if a train is coming. You can hear a train coming much earlier through the tracks than you can through the air. Students can investigate sound with two cups and a string to carry the vibration. From the reading, you know that heat is a form of energy produced by molecular movement. The greater the thermal energy, the greater the kinetic energy and the higher the temperature. Temperature is a measure of the average kinetic energy of the molecules in a substance. The Celsius scale is the temperature scale used in science. Students can investigate heat and use temperature to track changes in thermal energy by heating the air around a thermometer with a hair dryer.

14 Slide 19 The Heat Curve Duration: 00:02:11 If you graph the temperature of a solid pure substance as heat energy is applied, you will obtain a graph similar to the one shown above for water (not to scale). This graph illustrates how the average kinetic energy (temperature) of water molecules changes with the input of heat energy. As the solid water molecules vibrate faster with the input of heat energy, the average kinetic energy (and therefore the temperature) of the sample increases. Notice what happens to the graph when the temperature reaches zero degrees Celsius. At the melting/freezing point, the temperature remains constant as all of the heat energy is used to melt the ice. Once all of the ice melts, the temperature of the liquid water begins to rise until it reaches its boiling/condensation point. At the boiling/condensing point, the temperature remains constant as all of the heat energy is used to vaporize (or boil) the liquid water. Once all of the water turns to vapor, the gaseous water continues to increase in temperature. Now let s look at the graph in reverse. If we start with water vapor, reverse the process, and remove heat from the system, vapor will condense into water at the boiling/condensation point. Once all of the gas condenses into liquid, the liquid will continue to lose heat until the melting/freezing point, and the water will freeze into ice. Once all of the liquid has turned into ice, the solid will continue to decrease it s temperature as long as heat energy continues to be transferred out of the sample.

15 Slide 20 Heat Transfer Review Duration: 00:00:05 Heat moves from high temperature to low temperature on this beach in three ways: conduction, convection, and radiation. Let s review this vocabulary from the reading assignment. 1. Which of the lines represents transfer of heat by convection? 2. Which of the lines represents transfer of heat by radiation? 3. Which of the lines represents transfer of heat by conduction? Slide 21 Presentation 2: Energy Transformations and Conservation Duration: 00:00:19 Advance mode: Auto In this section, we will explore Energy Transformations and Conservation. To meet the objectives, the teacher must understand energy transformations and the conservation of matter and energy. This foundational knowledge will help prepare teachers to guide EC-6 students in their study of the physical sciences.

16 Slide 22 Sources of Electricity Duration: 00:01:06 Slide 23 Follow the Flow of Energy Duration: 00:01:27 Human invention has applied the knowledge of the conservation of energy and energy transformations. We take advantage of natural resources' potential and kinetic energy and transform it into electricity for human use. Most of the electricity in the United States is generated by burning fossil fuels such as coal, natural gas, and petroleum. In this case, chemical potential energy is converted into electrical energy. The chemical potential energy stored in fossil fuels can also be converted into thermal energy for heating, cooking, and/or transportation. Solar panels absorb light energy and convert it into electrical energy. Electricity is then transferred through power lines to homes and businesses. Solar energy can also be used to boil water and create steam, which is used to spin turbines in electrical generators. Hydroelectric plants convert the mechanical energy of falling water into electrical energy as the water spins the turbines of electrical generators. Electricity is then transferred through power lines to homes and businesses. Let s apply the concepts of energy transfer and energy transformation and see how the conservation of energy can be seen in the real world. Follow the flow of energy from the electrical cord to the pinwheel. Electrical energy flows through the conductive wires inside of the insulated cord. Electrical energy is transformed into heat energy in the hot plate. Heat is conducted from the hot plate to the water through contact between the hot plate surface and the bottom of the flask and through contact between the bottom of the flask and the water molecules. Heat is distributed throughout the water by convection currents. Heat energy transforms liquid water into gaseous water at 100 C. Heat energy is transformed into mechanical energy as pressure builds in the flask and steam escapes through the tubing. (Some heat is also transferred by conduction as water vapor molecules collide with the sides of the glass tubing.) The mechanical kinetic energy of flowing steam transforms into the mechanical kinetic energy of a spinning pinwheel. The steam-powered pinwheel is one way that students can investigate and

17 study conservation of energy through energy transformations and transfer. You will review additional examples in the Earth Science and Life Science sections. Slide 24 Presentation 2: Summary Duration: 00:00:07 Advance mode: Auto You have completed Presentation Two, Physical Science, in the Reviewing Science course. An understanding of matter and energy forms the foundation for understanding the natural sciences. In this presentation, we reviewed fundamental topics of forces and motion, properties of and changes in matter, and energy interactions and transformations. Students will benefit from participating in grade-appropriate activities that allow exploration of these topics throughout students early education to help support their development into a scientifically literate citizen.