Energy and Work: Forms, Kinetic and Potential Energy, and Machines

1. CHAPTERS 14&15 NOTES KONICHEK

2. I. Energy is the ability to do work. II Work is a transfer of energy.

3. Energy and Work III. Work and energy are closely related. A. Energy is known by the changes it causes. B .Work is done when a force moves an object through a distance. 1.Energy is transferred by a force moving an object through a distance. C. Both work and energy are typically measured in joules (J).

4. Energy and Work D.Energy has different forms. • The sun gives off energy in the form of heat and light.

5. Energy and Work • The sun gives off energy in the form of heat and light. 1. Plants convert sunlight into food. -PHOTOSYNTHESIS

6. Energy and Work Energy has different forms. • The sun gives off energy in the form of heat and light. • Plants convert sunlight into food. • People convert food energy into muscle movement.

7. V.The energy of motion is calledkinetic energy. A.The kinetic energy of any moving object depends upon its mass and speed. 1 Doubling the mass in the formula doubles the kinetic energy. • 2.Doubling the speed quadruples the kinetic energy.

8. VI. Potential Energy A.Potential energy is energy that is stored as a result of position or shape. B.Gravitational Potential Energy 1. Potential energy that depends upon an object’s height is called gravitational potential energy

9. 2.An object’s gravitational potential energy depends on its mass, its height, and the acceleration due to gravity.

10. C.The unit for height is meters. • 1. Height is measured from the ground or floor or some other reference level • D. Doubling either the mass of the object or its height doubles its gravitational potential energy. • E.Acceleration due to gravity, g, has a value in SI units of 9.8 m/s2 on Earth. • F.The unit for gravitational potential energy is joules.

11. G.Elastic Potential Energy 1.The potential energy of an object that is stretched or compressed. a.Something that is elastic springs back to its original shape after it is stretched or compressed.

12. VII. The major forms of energy are mechanical energy, thermal energy, chemical energy, electrical energy, electromagnetic energy, and nuclear energy.

13. A.All energy can be considered to be one of three forms: • 1.kinetic energy, • 2.potential energy, and • 3.energy in fields such as those produced by electromagnetic waves. B. Conservation of Energy-Each of these forms of energy can be converted into other forms of energy.

14. C.Mechanical Energy 1.The energy associated with the motion and position of everyday objects is 2.Mechanical energy is the sum of an object’s potential energy and kinetic energy.

15. D.Thermal Energy 1.The total potential and kinetic energy of all the microscopic particles in an object. 2.When an object’s atoms move faster, its thermal energy increases, and the object becomes warmer.

16. E.Chemical Energy 1.Chemical energy is the energy stored in chemical bonds. A.When bonds are broken, the released energy can do work. 1.All chemical compounds, including fuels such as coal and gasoline, store energy.

17. F.Electrical Energy 1.Electrical energy is the energy associated with electric charges. a.Electric charges can exert forces that do work.

18. G. Electromagnetic Energy-Originates from the electron levels of the atom-quantum physics 1.Electromagnetic energy is a form of energy that travels through space in the form of waves. a. Visible light and X-rays are examples of electromagnetic energy.

19. Lightning bolts transfer electric charge. • Galaxies are giant structures in space that typically contain billions of stars. The stars give off enormous amounts of electromagnetic energy.

20. H. Nuclear Energy 1The nucleus of an atom is held together by strong and weak nuclear forces, which can store an enormous amount of potential energy. a. The energy stored in atomic nuclei is known as nuclear energy. b. Nuclear fission releases energy by splitting nuclei apart. c.Nuclear fusion releases energy when less massive nuclei combine to form a more massive nucleus.

21. OH NO A NASTY WORD • I. WORK- THE MEASURE OF THE EFFECTS OF A FORCE OVER A DISTANCE • A. If the object doesn’t move , no work is done • 1. work= force x distance or • a.W=Fxd • 1. units Nxm = JOULE

22. Work done pitching

23. POWER TO THE PEOPLE • II. POWER- THE RATE WHICH WORK IS BEING DONE • A. POWER= WORK / TIME, • 1. P=W / T OR P= FXD / T • a. J/S= WATT

24. Hey, Hey, Hey • III. MACHINES AND MECHANICAL ADVANTAGE • A. MACHINE- ANYTHING WHICH MAKES WORK EASIER BY CHANGING THE DIRECTION OR DISTANCE THROUGH WHICH THE FORCE MOVES • 1. MULITPLYING THE FORCE

25. HEY YA NEVER GET SOMETHING FOR NOTHING! • B. WORK INPUT EQUALS WORK OUTPUT (WI=WO ) • 1. Fidi=Fodo • 1. MAY USE LESS FORCE, BUT HAVE TO MOVE IT A GREATER DISTANCE. • a. GETTING UPSTAIRS.

26. WHO’S ADVANTAGE? • C. MECHANICAL ADVANTAGE-TELLS THE AMOUNT A MACHINE INCREASES A FORCE. • 1. A LONG RAMP PROVIDES A GREATER M.A. THAN A SHORT RAMP

27. KONO IS BALD-HIS ADVANTAGE • D. TYPES OF MECHANICAL ADVANTAGE • 1. IDEAL M.A.(IMA)= EFFORT DISTANCE / RESISTANCE DISTANCE • a. IMA= ED/RD • 1. DOESN’T DEAL WITH FRICTION • 2. ACTUAL M.A(AMA).= RESISTANCE FORCE / EFFORT FORCE • a. AMA= RF/EF • 1. DEALS WITH FRICTION

28. KONO’S MIND IS AN EFFICIENT MACHINE • E. Machine Efficiency- This is the ratio of the work out to the work in • A .%E= {Work out/ work in}x100 • 1. %E= {Wo/Wi }x100 • 2. %E= (AMA/IMA)x100 • B. Increasing Efficiency • 1. lubrication, smoothing

29. It goes click cluck chug chug • IV. SIMPLE MACHINE- any thing which makes work easier by changing the distance or direction of the force • A. THE 2 BASIC MACHINES ARE LEVERS AND INCLINE PLANES. • 1. All other machines are variations of these 2

30. Whiz.fizz, boom, bang • VII SURVEY OF THE MACHINES • A. LEVER FAMILY- A LEVER IS A BAR OR BOARD FREE TO TURN ABOUT A FIXED POINT. • 1. FIXED POINT IS A FULCRUM • 2. TYPE OF LEVER DEPENDS UPON WHERE THE FULCRUM IS • B. FIRST CLASS- THE FULCRUM IS BETWEEN THE RESISTANCE FORE AND THE EFFORT FORCE –EXAMPLE-TEETER TOTTER. • C.SECOND CLASS- THE FULCRUM IS AT ONE END AND THE RESISTANCE FORCE IS IN THE CENTER AND THE EFFORT FORCE IS AT THE OTHER END- example-WHEEL BARROW. D. THIRD CLASS LEVER- THE FULCRUM IS AT ONE END. THE EFFORT FORCE IS IN THE CENTER AND THE RESISTANCE FORCE IS AT THE OTHER END . EXAMPLE IS THE FOREARM • 1. M.A FOR LEVERS: • A. IMA= EFFORT DISTANCE / RESISTANCE DISTANCE • 1. IMA= ED/RD

31. 3 classes of levers

32. You have to be pullying my leg • D. PULLEYS- A FIRST CLASS LEVER WHICH ROTATES ABOUT THE FULCRUM • 1. SINGLE FIXED PULLEY-CHANGES THE DIRECTION OF THE FORCE- PULLEY---M.A. IS 1- FORCE IN GETS AN EQUAL FORCE OUT. • 2. BLOCK AND TACKLE- MULTIPLE PULLEY SYSTEMS. • a. CHANGES THE DIRECTION OF THE FORCE AND PROVIDES A M.A • 3. THE M.A. IS EQUAL TO THE NUMBER OF SUPPORT ROPES OF THE SYSTEM.

33. Single fixed pulley

34. Movable pulley

35. Hey I’m a big wheel, but some people think I’m an axle • E. WHEEL AND AXLE-A WHEEL OR PULLEY CONNECTED TO A SHAFT. • 1. STEERING WHEEL OF A CAR • a. door knob • 2. M.A= WHEEL RADIUS / AXLE RADIUS • a. IMA= WR/AR • 3. To increase M.A. The wheel radius must be made larger

36. Wheel and axle

37. Very nice family • 2. INCLINE PLANE FAMILY • A. INCLINE PLANE(RAMP) A SLANTED SURFACE USED TO RAISE AN OBJECT. • 1. BY INCREASING THE LENGTH OF THE INCLINE THE M.A. INCREASES • a. turns a small effort force into a large output force. • 2. IMA= LENGTH / HEIGHT. • B. WEDGE- TWO INCLINE PLANES PUT BACK TO BACK- THE WEDGE DOES THE MOVING THROUGH THE SUBSTANCE- NAIL, KNIFE, WOOD WEDGE. • C. SCREW- AN INCLINE PLANE WRAPPED AROUND AN CYCLINDER. • 1. THE MORE THREADS ON THE SCREW THE GREATER THE M.A.

38. Incline plane

39. WEDGE

40. Want to play with my wedge?

41. SCREWING AROUND?

42. Screw moves through a substance

43. VI COMPOUND MACHINE-A MACHINE MADE UP OF ONE OR MORE SIMPLE MACHINES • A. bicycle- levers pulleys, wheel and axle

44. Can you name the simple machines that make up this compound machine