TAKS Objective 5

1. TAKS Objective 5 Motion , Forces and Energy

2. Energy Is defined as the Ability to do Work Energy has Two Types: • Kinetic (Energy of Motion) and • Potential (Stored Energy)

3. Kinetic Energy KE = ½ m v 2 Ex: A moving car has the ability to do work on the light pole if it hits it.

4. Potential Energy2 possibilities Gravitational PE -Object lifted to some height Elastic PE - A stretched or compressed object (spring or rubber band)

5. Gravitational Potential Energy or Will it fall? GPE = m g h m is the mass of the object in Kg, g is the acceleration due to gravity which is 9.8 m/s2 on earth and h is the height in meters

6. Use the formula page! PE = mgh 41 What is the potential energy of the rock? A 59,900 joules B 64,600 joules C 93,100 joules D 121,600 joules m = 95 kg g = 9.8 m/s2 h = 100 m 95 kg x 9.8 m/s2 x 100 = 93,100 joules C

7. Law of Conservation of Energy • Energy can change forms, but is never created nor destroyed • Loss in one form = gain in an another form • A falling object speeds up as it falls to the ground; PE decreases as KE increases. The KE it has at impact = the PE it had before it fell.

8. Example: A falling object speeds up as it falls to the ground; PE decreases as KE increases, the KE it has at impact with the ground is equal to the PE it had before it fell

9. Energy can be conserved in Non-Mechanical forms The chemical energy in a battery transforms into electrical energy Any reaction where more energy is given off than is used to start it is Exothermic An Endothermic reaction absorbs energy and causes cooling

10. Thermal Energy A body contains internal KE due to the motion of its atoms ( they are constantly wiggling and jiggling) Thermal Energy is the total internal KE of a body Temperature is the average KE of a body

11. 3 Ways that Heat Moves • Conduction Occurs when items are touching each other • Convection Fluids (liquids or gases) move • Radiation Movement through space

12. Heat moves by conduction in solids since the particles are close together and vibrate. . . Heat convection occurs in gases and liquids. Heat convection does not occur in solids because solids are unable to — A absorb heat by vibrating B transfer heat by fluid motion C emit radiation by reflecting light D exchange heat by direct contact Solids do radiate heat to their surroundings

13. The primary way liquids and gases transmit heat is by the process of — F reflection G conduction H radiation J convection Fluid heat movement is convection. Fluid motion occurs in liquids and gases.

14. Radiation – Transfer of Electromagnetic (E.M.) Energy • Objects are heated when exposed to infrared radiation • The suns heats the earth by sending infrared radiation along with other forms of E.M. energy 3.0 x 108 meters through empty space

15. Nuclear Reactions Fusion occurs when two atoms combine to form a new element. The sun produces all of its energy through fusion. Two hydrogen atoms combine to form a Helium atom from the great gravitational forces and pressure in the sun’s core

16. Nuclear Reactions - Fission • Fission is the splitting of nucleii of large atoms such as Uranium and Plutonium • Produces large amounts of infrared radiation and other forms of E.M. Energy such as Gamma Rays • Currently, it is the main form of Atomic Energy on Earth

17. Radiant Energy or Electromagnetic Energy (EM) • All radiant energy travels at 3.0 x 108 m/sec in space • Velocity of a wave = wavelength x frequency • Visible light is just one type of EM Energy

18. Electromagnetic Spectrum All of the forms of radiation given off by vibrating electric charges Radiation comes in the form of vibrating or “throbbing bundles of energy” called photons The frequency of the vibrating electric charges determines which type and how much energy will be given off

19. The entire E.M. Spectrum in order from lowest to highest frequency • Radio waves: AM and FM • Microwaves: cooking • Infrared: heat • Visible: (ROYGBV) • Ultraviolet: tanning • Xrays: medical • Gamma: deadly radioactivity

20. Waves - Energy carried by rhythmic disturbances • Two types: • 1. E.M. radiation move through empty space • 2. Mechanical require a medium (air, water or any type of matter) for movement • All waves carry ENERGY

21. Waves - 2 Types

22. All waves have similar properties • Frequency- the number of vibrations per second or the speed of the movement of the vibrating particles • Amplitude – the size of the movement of the vibrating particles • Velocity – how fast it travels • Wavelength – distance from a point on one wave to the same spot on the very next wave

23. Velocity of all waves - v=f λ f-frequency and λ is wavelength (distance between identical points on two consecutive waves) Reflection- bounce off barriers in regular ways Refraction- waves can change direction when speed changes

24. And the answer is? J 3300 Hz At 0°C sound travels through air at a speed of 330 m/s. If a sound wave is produced with a wavelength of 0.10 m, what is the wave’s frequency? F 0.0033 Hz G 33 Hz H 330 Hz J 3300 Hz Use the formula chart!!! Velocity = f λ OR 330 m/s = f x 0.10 m

25. Transverse Waves • In Transverse Waves particles vibrate at right angles to the direction the wave travels. • Ex. E. M. Waves, waves on a slinky or rope coil, ocean waves

26. Longitudinal or Compress ional Waves Vibrating particles move back and forth along the direction of the wave velocity Parts consist of compressions and rarefactions Ex. Sound Waves

27. Sound Waves are Compression Waves Sound is produced when a compression is made. It requires a producer and a medium to travel through. The more elastic the object, the faster sound travels.

28. Sound acts like other waves • Echoes are reflected sound waves • Sonar uses echoes to judge distance to obstructions • Human hearing is 20-20,000 Hz, below 10 Hz is infrasonic, and above 20,000 Hz is ultrasonic.

29. Sound Waves move through matter not through empty space. One tuning fork is struck and placed next to an identical fork. The two forks do not touch. The second tuning fork starts to vibrate because of — F interference G the Doppler effect H resonance J standing waves Resonance is the vibration of another object struck by a wave of the correct frequency. Since the forks are identical, the second one receives the correct frequency to begin vibrating.

30. Forces and Motion • Forces can create changes in motion (acceleration) • Deceleration is negative acceleration

31. Motion can be described as • a change in an object’s position • Average velocity (speed) is the change of position of an object over time

32. Velocity Graphs V = distance time • Velocity (v) is the slope (rise over run) of a position (d) vs. time (t) graph

33. The diagram represents the total travel of a teacher on a Saturday. Which part of the trip is made at the greatest average speed? F Q G R H S J T How do we work this one? Calculate v = d/t for each segment.

34. Acceleration Graphs • Acceleration (a) is the slope of a velocity (v) vs. time (t) graph • Plotted on a distance vs. time graph, acceleration is an exponential curve

35. Acceleration is a change in an objects velocity (speed or direction) • When an object’s speed changes over time it is accelerating (or decelerating) • A = vfinal – vinitial time • Units for acceleration m/s/s or m/s2

36. Definition of a Force • A Force is a push or a pull

37. Balanced Force • A force that produces no change in an object’s motion because it is balanced by an equal, opposite force.

38. Are forces that results in an object’s motion being changed. Unbalanced Forces +

39. Friction A force that acts in a direction opposite to the motion of two surfaces in contact with each other.

40. Friction Friction causes an object to slow down and stop. Since the amount of energy stays constant, the energy becomes heat.

41. Newton’s 1st Law of Motion • Object in motion stays in motion

42. Newton’s 1st Law of Motion • And Objects at rest stay at rest

43. Newton’s 1st Law of Motion • Until they are acted upon by unbalanced forces.

44. Inertia or Newtons 1st Law • Tendency for an object to stay at rest or moving in a straight line at a constant speed. • The mass (m measured in kg) of an object determines its inertia

45. Newton’s 2nd Law of Motion Force = Mass X Acceleration F=ma Weight (pull of gravity) is a commonly measured force, calculated by F=mg, g is the acceleration due to gravity 9.8 m/s2

46. Newton’s 2nd Law of Motion The greater the mass of an object, the greater the force required to change its motion.

47. Newton’s 2nd Law of Motion • The greater the acceleration of an object, the greater the force required to change its motion.

48. The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s2, what is the net force the frog exerts on the lake’s bank when leaping? • A 0.2 N • B 0.8 N • C 1.5 N • D 6.0 N Formula chart says F=ma, m is mass in kg, a is acceleration in m/s2. So, .5 kg x 3 m/s2= 1.5 N

49. Newton’s 3rd Law of Motion • For every action force there is an equal and opposite reaction force.

50. All forces come in action-reaction pairs Ex: feet push backward on floor, the floor pushes forward on feet Newton’s 3rd Law of Motion