Learning Outcomes for test #15 Unit 3, lessons 3 and 4 Name: ______________________________ Test Date: ___________________________ Vocabulary: Students need to learn and understand the meaning of the following vocabulary words AND be able to apply them to a variety of situations. KNOW THESE DEFINTIONS BACKWARDS AND FORWARDS!!!! 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. energy –the ability to perform work or change an object work –the use of force to move an object a certain distance or change an object potential energy – energy stored in the position or the structure of an object chemical potential energy – the energy in the links between atoms and molecules; food contains energy stored in the chemical bonds between atoms elastic potential energy – the energy stored by something that can stretch or compress, such as a stretched rubber band or spring gravitational potential energy – the energy an object possesses due to its position above Earth’s surface kinetic energy –the energy of a moving object law of conservation of energy –the theory that states that energy may change form, but it cannot be c created or destroyed. electrical energy –energy that comes from the movement of charged particles thermal energy –energy due to the motion of particles in matter mechanical energy – the sum of potential energy and kinetic energy circuit –a loop formed when electric current passes through an unbroken path of conductors electric current – a flow of electricity through a conductor shadow – a dark area produced when an object blocks the passage of light solar radiation – energy from the Sun that shines on Earth Students will learn in class about the following topics. Be prepared to be assessed on them. 1. Work is equal to the force used multiplied by the distance over which the force was applied. The unit for both work and energy is the unit of force times the unit of distance: the Newton-meter (N-m). Ex. If you can lift a box that weighs 10 N onto a shelf that is 1.5 m high, you are performing 15 N-m of work. Newton-meters are also known as joules (J). Like work, energy is measured in joules. W=force x distance 2. Why is no work being done when someone is pushing a car but it is not moving? Work is only done when the object that is receiving the force moves from one location to another. 3. Three boys were playing with basketballs. One boy was dropping the ball, one boy was throwing a ball, and one was lifting the ball. Which activity involves an increase in potential energy? The boy lifting the ball has an increase in potential energy. The ball is gaining potential energy as it is being lifted higher above the ground. 4. There is stored chemical energy in an unlit match. When the match burns, this energy is released. 5. A boulder sitting at the top of a hill, a child at the top of a slide, and a diver at the top of a diving board have gravitational potential energy. Anytime an object is raised above the ground, the potential energy it gains is gravitational potential energy. The greater the object’s weight and height above the ground, the more gravitational potential energy it gains. 6. ***Explain what forces and energies that a roller coaster has. Roller coasters have potential and kinetic energies. When the roller coaster is at the top of the hill, it has potential energy. When it rolls down the hill, it has kinetic energy. The forces of gravity and friction are also evident: gravity pulls the cars downward, and friction between the wheels and the track slows the car’s movement. 7. The amount of kinetic energy an object has depends on the object’s velocity. The faster an object is moving, the more kinetic energy it has. An object with a greater mass will have more kinetic energy than an object with a smaller mass. 8. Heat is kinetic energy in the vibration of particles. Electricity is related to the kinetic energy of electrons. Sound is the kinetic energy of particles as they move in waves. Light is also kinetic energy that moves in the form of waves. All forms of energy can perform work. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. Potential energy can easily change to kinetic energy. Vibrating like a spring is called periodic motion. In periodic motion, energy changes back and forth from potential to kinetic. If an object is not moving, it does not have kinetic energy. Kinetic energy is changed into heat energy through the work of friction. The kinetic energy of falling water is changed into electricity at a hydroelectric dam. Electrical energy can be changed into thermal, light, and mechanical energy. Chemical energy is stored in the particles that make up food and other fuels. When you eat, chemical energy passes to you. When you move, your muscles change the chemical energy from the food you ate into mechanical energy. Nuclear energy is potential energy stored in the links between protons and neutrons in an atom. The nuclear energy of the Sun becomes forms of energy such as light. This provides energy for Earth. All types of energy can be transformed into other types of energy. Mechanical energy is the sum of kinetic and potential energy. Moving objects have mechanical energy. Electric motors change electrical energy into mechanical energy in toys, washing machines, drills, and other tools. The Sun is the main source of light energy on Earth. Plants convert sunlight into chemical energy during photosynthesis. When a lightbulb is turned on, electrical energy is converted to light and heat energy. The more thermal energy a substance has, the warmer the substance is. Voltage sources increase the strength of electrons moving in the circuit. Batteries are a voltage source. A switch is a device that can open or close the path. An object in an electrical circuit that resists the flow of electrons is called a resistor. This energy can be transformed into heat or light. A lightbulb is a resistor. The amount of electric charge moving in a circuit is measured in units called amperes, or amps. ***How does energy change form in a flashlight? Chemical energy in the battery is transformed into electrical energy. Then electrical energy is transformed into light and heat by the resistor-the lightbulb. Why is it necessary to have a conductor in an electric circuit? A conductor allows electrons to move an electric current through a circuit. Without a conductor, electricity would not flow. Light is made of vibrating electrical and mechanical energy. This energy travels as a wave. Light waves vibrate in the direction perpendicular to the direction of their motion. They are called transverse waves. Wavelength is the distance between one peak and the next in a wave. Frequency refers to how many wave peaks pass a given point in one unit of time, such as a second. When you multiply the wavelength of a wave by its frequency, you get the speed of that wave. Although light is a wave of energy, it is also a particle. What properties of particles does light have? It travels in a straight line, it has momentum, and it hits objects. When light strikes an object’s surface, photons bounce off at random angles. This is called scattering light. Know the difference between opaque, translucent, and transparent – p. 122 in text A shadow is a dark area produced when an object blocks the passage of light. You can find the shape of a shadow by tracing light rays. As the Sun rises, the angle of the sunlight increases. This shortens your shadow. When the Sun is directly overhead, around noon, your shadow is at its shortest. Shadows depend on the angle and the distance between a light source and an object, and between the object and the place where the shadow is cast. The closer a light source is to an object, the larger the shadow an object will cast. A white shirt is cooler than a dark one on a sunny day because it absorbs less light. Energy from the Sun affects living and nonliving things. Examples of nonliving: Solar energy influences a region’s weather and climate. Solar energy drives the water cycle. How do plants make solar energy available to other organisms? They convert solar energy to chemical energy during photosynthesis.