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Class presentation slides for Physical Science 50 (second quarter) Spring Semester 2009

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1. 1. Aristotle Natural Motion
2. 2. Galileo Experimentation 
3. 3. Newton Newton’s Laws of Motion, Gravity 
4. 4. Linear Motion distance SPEED = time 
5. 5. Linear Motion displacement VELOCITY = time 
6. 6. Earth -> Sun 1.497 x 1011m distance velocity = 3 x 108m/s  Time = = 498.9 seconds = 8.3 minutes
7. 7. Sun -> Mars 2.28 x 1011m d 3 x 108m/s t = v= = 760.3 seconds = 12.67 minutes
8. 8. Acceleration change in velocity  Acceleration = time
9. 9. Deceleration = Negative Acceleration 
10. 10. Saleen S7 Turbo vf– vi 60 mph – 0 mph mph a= t = 3.3 s = 18.2 s = 0.005 mi/s2
11. 11. Gravitational Acceleration
12. 12. Free Fall Acceleration due to GRAVITY  Mass doesn’t matter 
13. 13. Gravitational Acceleration  Velocity increases at a constant rate vf - vi a= t 20m/s - 10 m/s = 1 second = 9.8 m/s2 = 32 ft/s2
14. 14. Distance Fallen Distance = Velocityaverage x time  v i + vf = 2 x t 0 + gt = 2 x t = 1/2 gt2
15. 15. Transamerica Building 46 g golf ball dropped  from top of Transamerica building  7.35 seconds to hit ground d = ???? 
16. 16. Transamerica Building 46 g golf ball dropped  from top of Transamerica building  7.35 seconds to hit ground  d = 1/2gt2 = (0.5)(9.8 m/s2)(7.35s)2 = 265 m = 853 ft
17. 17. g and elevation  ATT vs. Coors Field sea level 5280 ft 9.8185 m/s2 9.8136 m/s2
18. 18. G force Extreme Acceleration  > 1g Breathing difficulties  blackout
19. 19. Gravity
20. 20. Newton’s Laws of Motion Every body continues in a state of rest 1) or in uniform motion in a straight line unless compelled to change that state by forces impressed upon it. INERTIA
21. 21. Inertia
22. 22. Newton’s Laws of Motion 2) The acceleration produced by a Force acting upon on body is directly proportional to the mass of the body. F=mxa
23. 23. Force Units F =m x a  = 2000 kg x 0.05 m/s2 = 100 kg m/s2 = 100 Newtons
24. 24. Force of Gravity F=mxa  Fg = m x g  Fg = WEIGHT 
25. 25. Mass vs. Weight  60 kg person Weight = m x g Earth Moon Jupiter (60 kg)(9.8m/s2) (60 kg)(1.67 m/s2) (60 kg)(25.9 m/s2) 588 N 100 N 1552 N
26. 26. Weightlessness “less” gravity  NOT no gravity
27. 27. Newton & Gravity  1687  Principia “Every object in the  universe is attracted to and attracts every other object in the universe by a force called gravity”
28. 28. Gravitational Force  Mutually attractive force  Inverse square GM1M2 r2 where G  Fg = = 6.67 x 10-11Nm2/kg2
29. 29. g on Uranus? Fg = m x g = GM1M2/r2  G Mplanet g = rplanet2 (6.67 x 10-11 Nm2/kg2)(8.44 x 1025 kg) g =(2.56 x 107 m)2 g = 8.59 m/s2
30. 30. Size of Gravitational Force (6.67 x 10-11 Nm2/kg2) (60 kg)(60 kg)  Fg = (1 m)2 Fg = 2.4 x 10-7 N 
31. 31. Size of Gravitational Force (6.67 x 10-11 Nm2/kg2) (6 x 1024 kg)(7.35 x 1022kg) Fg =  (3.83 x 108 m)2 Fg = 2 x 1020 N
32. 32. Escape Velocity d = 1/2gt2 for objects in free fall  2d = gt2 but t = v/g for free fall 2d/g = t2 = (v/g)2 2 dg = v2 √2dg = v = ESCAPE VELOCITY
33. 33. Escape Velocity vE = √2dg = √2gREarth = √2(9.8m/s2)(6.378 x 106 m) = 11.18 X 103 m/s
34. 34. How high will it go? V2 = 2dg V2/2g = d (10 m/s)2 2 (9.8 m/s2) =d d = 5.1 m
35. 35. Newton’s Laws of Motion In the absence of outside  forces, the total momentum of a set of objects remains the same no matter how the objects interact with one another. p=mv 
36. 36. Conservation of Momentum m vbefore = m vafter  (3000 kg)(10m/s) + (1000 kg)(0 m/s) = (3000 kg)v’ + (1000 kg) (15 m/s) 30,000 kg m/s = (3000 kg) v’ + 15,000 kg m/s 15,000 kg m/s = (3000 kg) v’ -------> v’ = 5 m/s
37. 37. Conservation of Momentum m vbefore = m vafter  (2000 kg) (8 m/s) + (50 kg) (0 m/s) = (2000 + 50 kg) v’ 16,000 kg m/s ÷ 2050 kg = v’ = 7.8 m/s
38. 38. Inelastic Collisions (2 kg)(10 m/s) 3 kg v’ =? v = 0 m/s
39. 39. Elastic Collisions (2 kg)(10 m/s) 3 kg v’ =? v = -2 m/s
40. 40. Angular Momentum m1 x v1 x r1 = m2 x v2 x r2 
41. 41. Circular Motion 2 r = diameter  2πr = circumference  Magnitude of v doesn’t  change but direction does
42. 42. Centripetal Acceleration v a= t  vt - vb = 1/2(2 r)/v 2v = r/v v2 mv2 ac = rFc = r
43. 43. Applications Spin cycle  washer
44. 44. Car turning
45. 45. The ROTOR
46. 46. Centripetal Force mball = 0.25 kg r = 0.5 m v = 2 m/s Fc = ?
47. 47. Centripetal Force mball = 0.25 kg r = 0.5 m v = 2 m/s (0.25 kg)(2 m/s)2 Fc = 0.5 m = 2 Newtons
48. 48. Roller Coaster Loop Fc> Fg  mv2 r > mg V2/r > g
49. 49. Conservation of Energy The Energy of the Universe  Is neither created nor destroyed; It merely changes form.
50. 50. Forms of Energy
51. 51. Work and Power W=Fxd  work Power = time 
52. 52. Work W=Fxd  W=mxgxd  W = (50 kg)(9.8m/s2)(5m)  = 2450 kg m2/s2 = 2450 Joules
53. 53. Power Work  Power = time 2450 J = 30 s = 81.67 J/s = 81.67 Watts
54. 54. Kinetic Energy Work = F x d = (m x a) x d If d = 1/2at2 and v = at then d = 1/2a(v/a)2 = 1/2v2/a W = m a d = m a (1/2 av2/a) = 1/2mv2
55. 55. Potential Energy Potential Energy = m x g x h
56. 56. Potential & Kinetic Energy  PE + KE = Total Energy  PEtop = KEbottom mgh = 1/2mv2  2gh = v2  V = √2gh 
57. 57. Escape Velocity vE = √2dg = √2gREarth = √2(9.8m/s2)(6.378 x 106 m) = 11.18 X 103 m/s
58. 58. Terminal Velocity 1 Kg book falls 1 meter vf = ? V = √2gh = √2(9.8m/s2)(1m) = √19.6 m2/s2 = 4.4 m/s
59. 59. How tall is the incline? V = 5.42 m/s  V = √2gh  Thus h = v2/2g = (5.42 m/s)2/2(9.8 m/s2) = 1.5 m
60. 60. Roller Coaster
61. 61. Pole Vault World Record = 6 m  V = √2gh  = √2 (9.8m/s2)(6 m) = 10.9 m/s
62. 62. Heat transfer Heat:  Energy transferred between 2 systems in contact and at different temperatures
63. 63. Temperature Average kinetic energy  of atoms or molecules
64. 64. Temperature scales
65. 65. Biological Temperature Regulation Human: 37 C = 98.6 F  Shivering, flushing 
66. 66. Biological Temperature Regulation Birds  Animal fat layer 
67. 67. Specific Heat The Amount of heat  energy necessary to raise the temperature of a given substance
68. 68. Heat Energy Heat Energy Q Q=mC T C in units of Joules/g °C or calories/g °C
69. 69. Heat Capacity C
70. 70. Calories 1 calorie: amount of heat needed to raise temp of 1.0 gram H2O 1° C
71. 71. Dietary Calories 1 Calorie = 1000 calories 100 Calories 100,000 calories!
72. 72. Calorie burning
73. 73. Heat Transfer Wooden vs. Aluminum  Each pot contains 500 cal. Each spoon 100 g How hot will each one get?
74. 74. Heat Transfer  Aluminum spoon Q = mC T = 500 cal = (100g)(0.22cal/gºC) T 500 cal T = (100g) (0.22cal/gºC) = 22.73°C
75. 75. Heat Transfer  Wooden spoon Q = mC T = 500 cal = (100g)(0.58cal/gºC) T 500 cal T = (100g) (0.58cal/gºC) = 8.82°C
76. 76. Identifying Unknowns  A 400 g metal w/3680 Joules of Heat Temp 50°C -> 60°C What is C? Q C=m T = 3680 J/400g (10°C) = 0.92 J/g °C
77. 77. Limiting Heat Transfer Cair = 0.17 cal/g°C 
78. 78. Refrigeration
79. 79. Sound Energy Result of Vibrations  Air molecules disturbed  Ear membrane vibration  Auditory nerve -> Brain 
80. 80. Hearing
81. 81. Cochlea
82. 82. Waves
83. 83.  Wavelength: distance between crests( )  Frequency: # crests pass a given pt/time (f)  x f = velocity of sound (m) (1/sec) 1/sec = HERTZ
84. 84. Infrasound f of elephant communication  if is 34 m? fx = vs = 340 m/s vs Thus f = = 10 1/s = 10 Hz
85. 85. Ultrasound f of dolphin communication  if is 0.0034 m? fx = vs = 340 m/s vs = 105 Hz Thus f =
86. 86. Audible Sound Waves  Hearing range for normal human: 20 - 20,000 Hz  S,z,c sounds vs.  M,b sounds
87. 87. Sound & Medium Velocity of sound in different media 0º C air 331 m/s Helium gas 970 m/s Fresh water 1493 m/s Salt water 1513 m/s Granite 6000 m/s
88. 88. Sound & Temperature  vs = vo + (0.61 m/sºC)T
89. 89. Hot Day vs. Cold Day 110° F vs. –30 ° F?  At 110° F = 43.33 °C vs = 331 m/s + (0.61m/s °C) (43.3 °C) = 357.43 m/s At –30 ° F = –34.4 ° C vs = 331 m/s + (0.61m/s °C) (–34.4 ° C) = 310 m/s
90. 90. Echolocation Bat sends signal and  receives echo 0.7 s later in 4° C cave -- how far is the wall? vs = 331 m/s + (0.61m/s °C) (4°C) =333.4m/s d = v x t = vs x t/2 = (333.4m/s)(0.35s) =116.7 m
91. 91. Sound Intensity Bel = 10 db  intensity doubling (d2)2 I1 (d1)2 = I2 2 Intensity drops with (distance)
92. 92. Sound Intensity
93. 93. Intensity comparison  Standing 2 m vs. 200 m from jet taking off? (200m)2 120 db (2 m)2 x 40000/4 = 105 = 5 factors of 10 x = 70 db
94. 94. Doppler Effect
95. 95. Doppler Effect  Approaching sound f Vs f’ = f VS - V  Retreating sounds f Vs f’ = f VS + V
96. 96. Doppler Example Approaching at 30m/s: 340m/s f’ = (440 Hz) 340 - 30 m/s = 483 Hz Retreating at 30 m/s: 340m/s f’ = (440 Hz) 340 + 30 m/s = 404 Hz
97. 97. Medical Doppler Blood flow velocity  F= 80000 Hz, f’ = 80020 Hz f’ vs 1500 m/s f = vs - v = 1.00025 = 1500 - v m/s => v = 0.375 m/s = 37.5 cm/s
98. 98. Sonic Boom
99. 99. Music Pythagoras   Octave = 2 f  Harmonious frequencies = simpler ratio