2012 PVHS NHSPE Review Science

1. 2012 PVHS NHSPE ReviewScience Physics Part 1… Energy

2. What we need to know… • Which of the following examples has the greatest thermal (internal) energy? • 5 kg of water with a temperature of 150°C • 8 kg of water with a temperature of 110°C • 10 kg of water with a temperature of 90°C • 100 kg of water with a temperature of 28°C

3. 2. A ball is initially dropped from a height 4 meters. After the ball bounces it returns to a height of only 2 meters. How much of the ball’s initial gravitational potential energy was transformed between the initial position and the final position of the ball? • One fourth of the total energy. • Half of the total energy. • Double the total energy. • Four times the total energy.

4. Energy is created as the result which activity? • Burning gasoline in an internal combustion engine. • Damming a river for hydroelectric power. • Rolling a marble down an incline plane. • Energy can only be transformed, not created.

5. Aluminum was once used as the wires in home construction. Recently, it was changed to copper wires. Which of the following statements BEST account for why aluminum was replaced with copper? • When electrical energy is passed through a copper wire, less of the energy removes copper atoms from the wire. • The electrical energy that a copper wire can transfer is less than an aluminum wire. • As a byproduct of transmission, more electrical energy is transformed to wasted thermal energy in aluminum wire than in copper • The electrical energy that passes through an aluminum wire cannot be directed as well as the energy passing through copper.

6. In an alternating current (AC) circuit, • voltages can be easily increased and decreased within the circuit allowing for lower energy losses during transmission. • voltages change direction several times a second to generate electrical charge more rapidly. • rapid current changes regulate the ease at which electricity passes through the circuit. • current most often is high to prevent energy losses during transmission, but can be low to decrease the voltage in the circuit.

7. Which of the following describes how a dam creates electricity? • Water is heated up and creates steam to turn the generator to create electricity. • Gravitational potential energy transfers to kinetic energy which turns a generator. • Electrons are removed from the water as it passes and creates electricity. • Water flows over wires in the dam which creates current from the water.

8. A hammer strikes a nail and drives the nail into a block of wood. If the action force is the hammer striking the nail, the reaction force is • the nail striking the wood with an equal and opposite force. • the nail striking the hammer with an equal and opposite force. • the wood striking the hammer with an equal and opposite force. • the wood striking the nail with an equal and opposite force.

9. Which of the following would supply the greatest acceleration when applied to a 10 kg mass? • 5N • 10N • 15N • 20N

10. Use the diagram to answer the question below. A cart is being pulled North across a carpeted floor. Which direction is the force of friction acting? • North • South • East • West

11. You have created a track out of cardboard for a marble to travel down. In order for the marble to complete the track, why does the first hill have to be the highest? • The friction caused by the track resists the motion of the marble. • The friction caused by the track increases the motion of the marble. • Gravity is pulling down on the marble causing it to slow down. • Gravity is pulling down on the marble causing it to speed up.

12. What is Energy? • Energy is… • The ability of an object to produce a change in itself or its environment • It is a measure of the capacity to produce change. • Sometimes Work is associated with change • Work transfers energy, but energy can also be transferred by Heat and Radiation

13. … stretching the bow transfers chemical energy from your muscles into potential energy in the bow and string … releasing the arrow transfers potential energy in the bow to kinetic energy in the arrow Can Energy be Created? • Law of Conservation of Energy- Energy cannot be created or destroyed • Total amount of energy is constant • Energy can only be stored or transferred

14. Energy Capacity for change Sun light waves Can’t create or destroy • What is the earth’s primary energy source? • The sun releases the energy stored in atoms through Fusion • Fusioncombines the atoms of an element to create a different element • Energy is transferred to earth by Radiation • Electromagnetic waves like light • Higher frequency… higher energy radiation Transfer it Store it The sun does not “burn” and it does not “create” energy

15. Energy Capacity for change Sun Light Remember… Force is a pull or push on an object and is only related to energy by work… energy is not a force Waves Can’t create or destroy Radiation Transfer it Force X Work Store it Distance • How else can energy transfer? • Work transfers energy • Work is a Force that causes displacement (moves an object a distance) • W=Fxd • Whenever work is done there is Friction • Friction always opposes motion and causes energy loss to the environment Friction

16. Energy Capacity for change Sun Light Waves Can’t create or destroy Radiation Transfer it Force X • How else can energy transfer? • Heat also transfers energy • Heat is energy transferred between objects at different temperatures • Higher temp… faster atoms run into Lower temp… slower atoms • The random motion of atoms is Thermal Energy Work Store it Distance Heat Friction Vibrating atoms and molecules Thermal Energy

17. Energy Capacity for change Sun Light Waves Can’t create or destroy Radiation Transfer it Force X Work Store it Distance Heat Friction • Thermal Energy • Virtually every energy transfer involves friction and temperature differences • Some energy is always lost to the environment as thermal energy • We try to counteract this by designing more efficient devices Vibrating atoms and molecules Thermal Energy

18. Energy Capacity for change Sun Light Waves Can’t create or destroy • How is energy stored? • Kinetic energy is the energy stored in the motion of objects • Any object in motion has stored energy • KE = ½ mass x velocity2 • KE energy increases greatly with speed Radiation Transfer it Force X Work Store it Distance Kinetic Heat Friction Objects in motion Vibrating atoms and molecules Snowboarder Thermal Energy

19. Energy Capacity for change Sun Light Waves Can’t create or destroy • Thermal Energy is just energy stored in the kinetic energy of atoms Radiation Transfer it Force X Work Store it Distance Kinetic Heat Friction Objects in motion Vibrating atoms and molecules Snowboarder Thermal Energy

20. Energy Capacity for change Sun Light Waves Can’t create or destroy • How is energy stored? • Potential energy is energy stored because of an object’s position • Examples… • If you stretch a rubber band, it has more energy than its starting position • An object at a higher position has more energy than a similar object at a lower position • An electron in a higher orbit has more energy than it did in a lower orbit • Electricity and magnetism are also forms of potential energy Radiation Transfer it Force X Work Store it Distance Kinetic Heat Friction Potential Objects in motion Vibrating atoms and molecules Position Snowboarder Gravitational Elastic Chemical Thermal Energy Spring or Rubber Band Battery, TNT Food

21. Energy Capacity for change Sun Light Waves Can’t create or destroy Radiation Transfer it Force X Work Store it Distance Kinetic Heat Friction Potential Objects in motion Vibrating atoms and molecules Position Snowboarder Gravitational Elastic Chemical Thermal Energy spring or rubber band Battery, TNT Food

22. Energy Transfer Pie Chart Store Electrical Energy - Eelec Gravity Potential- PE Elastic Potential- Ee Chemical- Ec Kinetic Energy – KE Thermal Energy - Et Transfer Work - W Heat - Q Radiation A B C A B C Et Wgravity Wgravity Et PE PE Wfriction KE KE Wfriction

23. Practice and Demos • Create energy transfer pie charts for the following processes: • Bending a paperclip (on your own) • Movement of a pendulum • Solar Panel and motor • Spring and cart • Be sure to show what is causing the energy to transfer. • Follow the instructions and use the pie charts in the class set. • Abbreviations • Store • PE – Gravity Potential • KE – Kinetic Energy • Ee – Elastic Energy • Echem– Chemical Energy • Et – Thermal Energy • Eelec – Electrical Energy • Transfer • W – Work • Q – Heat • R - Radiation ******Begin your homework if you finish early ******

24. Physics Part 2… Force and Motion

25. Rolling Ball Grand Prix • Purpose: To observe an object in motion and determine what is necessary to change that object’s motion. • Materials: Butcher paper with track, timer, and a large marble. • Procedure: See who can roll the ball along the track the fastest using one finger. • Rules: • If the marble goes off the track pick it up and restart where the marble went out. Keep the timer running • You can not touch the marble at all in the “no touch” zone • Be sure to use only one finger • Answer the questions on the sheet as you go.

26. Rolling Ball Grand Prix • Describe the ball’s motion in the “no touch” zone. • Moves in a straight line • Speed stays about the same • What does the ball do in the corners or around the loop if you don’t push it? • Wants to keep going in the same direction • What can you say in general about the motion of an object that has no “force”? • Without a force, objects will move in a straight line at the same speed • This is basically Newton’s 1st Law of Motion… “An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force” • This is also called the Law of Inertia • Inertiais an object’s resistance to a change in motion • Massis a measure of inertia

27. Rolling Ball Grand Prix • How did you get the ball to speed up or slow down? • Push Harder in the direction it is rolling • Push opposite the motion • How did you get the ball to change direction? • Push in the direction you want the ball to go • What would you need to do differently if the ball was twice as large (had twice the mass)? • Push harder to get the same change in motion • Force is any push or pull on an object • To change the ball’s motion, you applied force • Acceleration (a) is the rate of change in velocity • Velocity is an object’s speed and direction • Force causes acceleration which changes speed or direction • Mass measures inertia, or resistance to change • More mass, less acceleration

28. Rolling Ball Grand Prix • Force is any push or pull on an object • To change the ball’s motion, you applied force • Acceleration (a) is the rate of change in velocity • Velocity is an object’s speed and direction • Force causes acceleration which changes speed or direction • Mass measures inertia, or resistance to change • More mass, less acceleration • This is the 2nd Law of Motion: • Increase force… increase acceleration • Increase mass… decrease acceleration

29. Rolling Ball Grand Prix • Which of the following would require the least amount of force,if applied to the same ball? • Stopping the ball that is rolling on a flat and smooth surface. • Changing the direction of a ball that is rolling on a flat and smooth surface. • Starting the ball in motion on a flat and smooth surface. • Keeping the ball moving at a constant speed on a flat and smooth surface. Answer D As the ball rolls there is a small amount of friction… if you don’t keep pushing the ball will slow To keep the ball rolling, at constant speed you just need to overcome friction A, B, and C require a change in motion To change the balls motion, you need to overcome both inertia and friction

30. Rolling Ball Grand Prix • What would happen if two object’s were racing on the same track and they collided? • Each would change speed and/ or direction… requires force • They exert force on each other • The forces are in opposite directions • This is the 3rd Law of Motion… “For every action there is an equal and opposite reaction” • Forces always occur in pairs that are equal and in opposite directions Examples… The earth exerts a 600N force on you, you exert the same force on the earth A Bat hits a ball, the ball hits the bat with the same force • A hammer strikes a nail and drives the nail into a block of wood. If the action force is the hammer striking the nail, the reaction force is • the nail striking the wood with an equal and opposite force. • the nail striking the hammer with an equal and opposite force. • the wood striking the hammer with an equal and opposite force. • the wood striking the nail with an equal and opposite force. Force Force

31. Graphs of Motion No acceleration Constant acceleration distance velocity acceleration time time time

32. Force What is a Net force? Net Force = sum of all force vectors

33. Force • Balanced Forces… • No Net Force • What happens? • Unbalanced Forces… • Net Force • What happens? *Nothing changes *Cart will Accelerateto the right What is a Net force? Net Force = sum of all force vectors

34. Force How are forces different? • Types of forces: • Contact forces- forces that happen when two objects touch • Field Forces- objects don’t touch but they still push or pull each other (Action-at-a-distance)

35. Types of Forces

36. Electrical force and magnetism are the same as gravity in varying with distance Field Forces • Gravitational Force • Any object with mass creates gravitational force… more mass, more force • the closer the object, the greater the force… • The force decreases rapidly as distance increases Small force Much Bigger force

37. What we need to know… • Which of the following examples has the greatest thermal (internal) energy? • 5 kg of water with a temperature of 150°C • 8 kg of water with a temperature of 110°C • 10 kg of water with a temperature of 90°C • 100 kg of water with a temperature of 28°C

38. Which of the following examples has the greatest thermal (internal) energy? • 5 kg of water with a temperature of 150°C • 8 kg of water with a temperature of 110°C • 10 kg of water with a temperature of 90°C • 100 kg of water with a temperature of 28°C D… temperature measures the average kinetic energy. To determine the greatest amount of energy, you need to consider mass or matter. Since it is all the examples are the same substance, just multiply the mass x temperature. Thermal energy is where all energy in a physical process ends up… the random motion of atoms and molecules… this point should be emphasized since several sample test questions allude to this.

39. 2. A ball is initially dropped from a height 4 meters. After the ball bounces it returns to a height of only 2 meters. How much of the ball’s initial gravitational potential energy was transformed between the initial position and the final position of the ball? • One fourth of the total energy. • Half of the total energy. • Double the total energy. • Four times the total energy.

40. 2. A ball is initially dropped from a height 4 meters. After the ball bounces it returns to a height of only 2 meters. How much of the ball’s initial gravitational potential energy was transformed between the initial position and the final position of the ball? • One fourth of the total energy. • Half of the total energy. • Double the total energy. • Four times the total energy. B… at the start the total energy equaled the gravitational potential, so if the ball only went ½ as high then only ½ the total was transformed… the other ½ was transformed into thermal energy.

41. Energy is created as the result which activity? • Burning gasoline in an internal combustion engine. • Damming a river for hydroelectric power. • Rolling a marble down an incline plane. • Energy can only be transformed, not created.

42. Energy is created as the result which activity? • Burning gasoline in an internal combustion engine. • Damming a river for hydroelectric power. • Rolling a marble down an incline plane. • Energy can only be transformed, not created. D… Energy cannot be created or destroyed, it can only be stored or transferred. Total energy remains constant, but different amounts can be transferred between different storage means like… thermal gravitational potential, kinetic, electric potential, chemical potential, etc…

43. Aluminum was once used as the wires in home construction. Recently, it was changed to copper wires. Which of the following statements BEST account for why aluminum was replaced with copper? • When electrical energy is passed through a copper wire, less of the energy removes copper atoms from the wire. • The electrical energy that a copper wire can transfer is less than an aluminum wire. • As a byproduct of transmission, more electrical energy is transformed to wasted thermal energy in aluminum wire than in copper • The electrical energy that passes through an aluminum wire cannot be directed as well as the energy passing through copper.

44. Aluminum was once used as the wires in home construction. Recently, it was changed to copper wires. Which of the following statements BEST account for why aluminum was replaced with copper? • When electrical energy is passed through a copper wire, less of the energy removes copper atoms from the wire. • The electrical energy that a copper wire can transfer is less than an aluminum wire. • As a byproduct of transmission, more electrical energy is transformed to wasted thermal energy in aluminum wire than in copper • The electrical energy that passes through an aluminum wire cannot be directed as well as the energy passing through copper. C… In any process or activity, some energy is lost as thermal energy. To increase efficiency, we want to minimize thermal losses.

45. In an alternating current (AC) circuit, • voltages can be easily increased and decreased within the circuit allowing for lower energy losses during transmission. • voltages change direction several times a second to generate electrical charge more rapidly. • rapid current changes regulate the ease at which electricity passes through the circuit. • current most often is high to prevent energy losses during transmission, but can be low to decrease the voltage in the circuit.

46. In an alternating current (AC) circuit, • voltages can be easily increased and decreased within the circuit allowing for lower energy losses during transmission. • voltages change direction several times a second to generate electrical charge more rapidly. • rapid current changes regulate the ease at which electricity passes through the circuit. • current most often is high to prevent energy losses during transmission, but can be low to decrease the voltage in the circuit. A… In any process or activity, some energy is lost as thermal energy. To increase efficiency, we want to minimize thermal losses.

47. Which of the following describes how a dam creates electricity? • Water is heated up and creates steam to turn the generator to create electricity. • Gravitational potential energy transfers to kinetic energy which turns a generator. • Electrons are removed from the water as it passes and creates electricity. • Water flows over wires in the dam which creates current from the water.

48. Which of the following describes how a dam creates electricity? • Water is heated up and creates steam to turn the generator to create electricity. • Gravitational potential energy transfers to kinetic energy which turns a generator. • Electrons are removed from the water as it passes and creates electricity. • Water flows over wires in the dam which creates current from the water. B… The vast majority of electricity we use is from generators. Generators produce electricity by rotating a wire (electrons) through a magnetic field. A generator can be turned many ways… primarily we use steam pressure (like steam shooting out of tea-kettle) or moving water to turn a turbine (like a windmill or waterwheel). Our powerplants use natural gas, nuclear fission, coal and oil to create steam to turn a turbine. Dams convert the gravitational energy stored in the water behind the dam into kinetic energy of moving water, as moving water turns the turbine which turns the generator.

49. A hammer strikes a nail and drives the nail into a block of wood. If the action force is the hammer striking the nail, the reaction force is • the nail striking the wood with an equal and opposite force. • the nail striking the hammer with an equal and opposite force. • the wood striking the hammer with an equal and opposite force. • the wood striking the nail with an equal and opposite force.

50. A hammer strikes a nail and drives the nail into a block of wood. If the action force is the hammer striking the nail, the reaction force is • the nail striking the wood with an equal and opposite force. • the nail striking the hammer with an equal and opposite force. • the wood striking the hammer with an equal and opposite force. • the wood striking the nail with an equal and opposite force. B… Newton’s 3rd Law, for every action, there is an equal and opposite reaction. If you push or pull (apply force) to something (anything), that something will push or pull on you in the opposite direction.