ESSENTIAL QUESTION What is the difference between positive and negative acceleration?
ACCELERATION Velocity – includes speed of an object and the direction of the motion. What is the difference between speed and velocity? Acceleration - rate of change of velocity. Acceleration occurs when an object changes speed, its direction, or both.
USE DOCUMENT CAMERA TO POST FORMULAS MAKE SURE TO ADD 2 TO ACCELERATION
ESSENTIAL QUESTION What is the difference between positive and negative acceleration? If speed increases, acceleration is positive. If speed decreases, acceleration is negative.
ACCELERATION PRACTICE PROBLEMS Find Velocity Initial Velocity Time (t) 1 26 m/s 20 m/s 6 s 2 0 km/s 12 km/s 4 s 3 8 m/s 3 m/s 2 s 4 46.4 m/s 27.3 m/s 11 s 5 5 m/s 15 m/s 5 s
FORCES Force – a push or pull applied to an object. Net Force – when two or more forces act on an object at the same time.
MOTION & FORCES Forces are = balanced forces Net force = 0 Forces unbalanced Net force = + Combined forces Net force = 2 forces added together
FRICTION Friction- the force that opposes the sliding motion of two touching surfaces. Friction is caused by microscope bumps on surfaces called microwelds.
Type of Friction DescriptionExample Static Friction in which two surfaces are not moving past one another. Pushing a fridge across the floor. Sliding Friction where two objects slide past one another. Sledding down a hill. Rolling Friction between a rolling object and surface it rolls on. Skateboard moving on ground. Fluid Friction when objects moves through fluid, meaning either a liquid or gas. Skydiving
AIR RESISTANCE Friction is like force that opposes motion of objects that move through air – depends on speed, size, and shape of object
ESSENTIAL QUESTION What does the force of friction between two objects in contact depend on? Kinds of surfaces and the friction pushing them together.
TYPES OF FRICTION PG. 8 Create a Four Point Envelope Foldable. Label Write definitions Draw an illustration Glue/tape to top of page Tape extra piece onto page 14 for future use
NEWTON’S FIRST LAW OF MOTION Also known as Inertia! An object in motion stays in motion or an object at rest stays at rest until an unbalanced net force acts upon it. Inertia – tendency of an object to resist change in its motion. Draw stationary ball, rolling ball into wall (look at notes)
NEWTON’S SECOND LAW OF MOTION A net force acting on an object causes the object to accelerate in the direction of the force. Force = mass X acceleration F = m X a Acceleration is determined by size of force and the mass of an object.
NEWTON’S THIRD LAW OF MOTION For every action (force) there is an equal or opposite reaction (force). Momentum – property of moving object resulting from its mass an velocity. Momentum (p) = mass X velocity
ESSENTIAL QUESTION Newton established his three laws of motion to do what? Newton’s Laws can be used to analyze and predict changes in motion on objects.
NEWTON’S COMIC STRIP Draw a 6 framed comic strip illustrating one of Newton’s Laws. Recommend using a rough draft page. Final copy is in the INB.
GRAVITY Gravity – any two masses that exert an attractive force on each other. Gravity depends on mass and distance between objects. Weight – gravitational force exerted on an object, measured in units called Newtons
PROJECTILE MOTION Projectile is anything thrown or shot through the air. A projectile follows a curved path and has either horizontal or vertical motion.
CENTRIPETAL FORCE Centripetal Acceleration – acceleration toward the center of a curved or circular path. Centripetal force– force toward the center of a curved or circular path.
What causes the path of a projectile to be covered? The path is covered by the vertical motion and horizontal motion.
ESSENTIAL QUESTION What is the difference between kinetic and potential energy?
ENERGY ENERGY – the ability to cause change. Forms of energy include: Electrical Chemical Thermal Radiant
KINETIC ENERGY Kinetic Energy – energy in the form of motion KE depends on mass and velocity of moving objects Example: Going down a slide
POTENTIAL ENERGY Potential Energy – energy that is stored Example of PE: waiting at the top of the slide Elastic Potential Energy – energy that is stored by something that can stretch or compress such as a rubber band or string.
POTENTIAL ENERGY Chemical Potential Energy – energy stored in chemical bonds. **A glass of milk has CPE until you drink it, then calories are used as energy for your body. Gravitational Potential Energy – anything that can fall has stored GPE. ***A ball on a ledge.
ESSENTIAL QUESTION What is the difference between kinetic and potential energy? Kinetic energy is energy in form of motion where potential energy is stored.
ENERGY Energy can be transformed from one form to another. Example: Lightbulb (Electric Energy) Light Energy Thermal Energy
MECHANICAL ENERGY total amount of kinetic energy and potential energy in a system. ME = PE + KE
THE LAW OF CONSERVATION OF ENERGY - energy may change form, but it cannot be created or destroyed under ordinary conditions.
THE LAW OF CONSERVATION OF ENERGY Friction converts mechanical energy in to thermal energy The breakfast you eat converts chemical energy into mechanical energy, heat energy so you r muscles can pump your legs. Air resistance converts ME into thermal energy.
ESSENTIAL QUESTION What law states that the total amount of energy never changes? The Law of Conservation of Energy.
FILMSTRIP DIRECTIONS: Cut out television and center square from the handout. Tape/Glue TV on top of existing TV. Please read directions and DO NOT attach on sides. After coloring illustrations on filmstrip, cut out filmstrip and slide behind television to see your illustration on the big screen. Write an explanation explaining your filmstrip on a separate sheet of paper and attach to pg. 17. Make sure you share how energy changed form.
TEMPERATURE Temperature -a measure of the average value of the kinetic energy of the molecules in random motion. (SI unit for temperature is Kelvin (K)). Thermal Expansion- almost all substances expand when they are heated and contract when they are cooled – *Exception water Thermal Energy- sum of the kinetic and potential energy of all the particles in an object; thermal energy of an object increases as temperature increases.
HEAT Heat - thermal energy that flows from something at a higher temperature to something at a lower temperature. Specific Heat- amount of heat needed to raise the temperature 1kg of some material by 1’C.
THERMAL ENERGY EQUATION Q. change in thermal energy (J) = mass (kg) X temp (‘C) X (‘C) Specific heat (J/(Kg)(c) Q = m (Tf – Ti) C
SPECIFIC HEAT OF COMMON MOLECULES Specific Heat of Common Molecules Substance Specific Heat (J/(kg’C) Water 4,184 Wood 1,760 Carbon 710 Glass 664 Iron 450
KINETIC ENERGY LAB FOLLOW DIRECTIONS Or you will loose the lab
KINETIC ENERGY LAB Matter, which is made up of tiny particles (atoms & molecules), is all around you. Those particles are in constant motion moving in all directions at different speeds. The measure of the average kinetic energy of those particles is temperature, which increases as the kinetic energy of the particles increases.
MATERIALS 2 – 200 ml beakers Water Food coloring Timer
DIRECTIONS 1.Pour 150 ml of room temperature water into Beaker A. 2.Pour 150 ml of hot water into Beaker B. 3.Put one drop of food coloring into each beaker. Record observation.
DIRECTIONS CONT. 4.Compare the two beakers for the next two minutes. At the end of each minute draw a colored sketch showing the water in each beaker in your data table. 5.Write a paragraph describing the results of your experiment. Make sure to use the following vocabulary in your description: water molecules, kinetic energy, temperature.
ESSENTIAL QUESTIONS How are conduction and convection different?
TRANSFERRING THERMAL ENERGY ConductionConvectionRadiation transfer of energy by thermal energy between particles in matter transfer of thermal energy in a fluid movement of warmer and cooler fluid from place to place transfer of energy by electromagnetic waves
CONDUCTION Conduction occurs in solids, liquids, and gases. Metal is the best conductor of heat.
CONVECTION Convection occurs in fluids. Rising of warmer fluid and sinking of cooler fluid forms a convection current.
TRANSFER HEAT The transfer of energy by radiation is most important in gases. Insulator- material in which heat flows slowly. EXAMPLES of best insulators: wood, some plastics, fiberglass, and air.
ESSENTIAL QUESTION Why can’t heat be converted completely to work?
FORCED AIR SYSTEM most common type of heating using a furnace to heat air then a fan blows air through ducts to rooms.
RADIATOR SYSTEMS closed metal container that contains hot water or steam which is transferred to surrounding air by conduction this warm air moves through rooms by convection.
ELECTRIC HEATING SYSTEMS electronically heated coils placed in floors and in walls heating surrounding air by conduction.
SYSTEMS USING SUN’S ENERGY Passive Solar Heating- radiant energy from the Sun is transferred to the room through windows. Active Solar Heating- systems that use solar collectors that absorb radiant energy from the Sun.
THERMODYNAMICS study of the relationship among thermal energy, heat, and work. 1 st Law of Thermodynamics 2 nd Law of Thermodynamics The increase in thermal energy of a system equals the work done on the system plus the heat transferred to the system. It is impossible for heat to flow from cool object to warm object unless work is done.
ESSENTIAL QUESTION Why can’t heat be converted completely to work? The 2 nd Law of Thermodynamics prevents it.