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Branches of Physics. Study of how things move without considering the cause of motion. This branch of physics only deals with describing how something.

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Presentation on theme: "Branches of Physics. Study of how things move without considering the cause of motion. This branch of physics only deals with describing how something."— Presentation transcript:

1 Branches of Physics

2 Study of how things move without considering the cause of motion. This branch of physics only deals with describing how something is moving using quantities like distance, position, displacement, speed, velocity and acceleration.

3 Branches of Physics Study of how things move or don't move without considering the cause of motion. This branch of physics only deals with describing how something is moving using quantities like distance, position, displacement, speed, velocity and acceleration. Kinematics

4 Branches of Physics Study of why things move or don't move in a certain way. This branch of physics deals with a quantity called “net force”, which determines whether something accelerates or doesn't accelerate. This branch of physics deals with the causes of motion.

5 Branches of Physics Study of why things move or don't move in a certain way. This branch of physics deals with a quantity called “net force”, which determines whether something accelerates or doesn't accelerate. This branch of physics deals with the causes of motion. Dynamics

6 Branches of Physics Study of why things move or don't move in a certain way. This branch of physics deals with a quantity called “net force”, which determines whether something accelerates or doesn't accelerate. This branch of physics deals with the causes of motion. Dynamics Study of both how and why things move, or Kinematics + Dynamics = ??

7 Branches of Physics Study of why things move or don't move in a certain way. This branch of physics deals with a quantity called “net force”, which determines whether something accelerates or doesn't accelerate. This branch of physics deals with the causes of motion. Dynamics Study of both how and why things move, or Kinematics + Dynamics = Mechanics

8 Famous Kinematic Quantities

9 Tells us how far something travels along a path

10 Famous Kinematic Quantities Tells us how far something travels along a path = distance or change-in distance

11 Famous Kinematic Quantities Tells us how far something travels along a path = distance or change-in distance A B

12 Famous Kinematic Quantities Tells us how far something travels along a path = distance or change-in distance A B Does depend on path taken

13 Famous Kinematic Quantities Tells us how far something travels along a path = distance or change-in distance A B d or Δd Does depend on path taken

14 Famous Kinematic Quantities Tells us the straight-line distance and direction from start to finish. A B d or Δd

15 Famous Kinematic Quantities Tells us the straight-line distance and direction from start to finish. “ Displacement” A B d or Δd

16 Famous Kinematic Quantities Tells us the straight-line distance and direction from start to finish. “ Displacement” A B d or Δd Does not depend on path taken, only start and finish

17 Famous Kinematic Quantities Tells us the straight-line distance and direction from start to finish. “ Displacement” A B d or Δd Does not depend on path taken, only start and finish Δd

18 Famous Kinematic Quantities Tells us the straight-line distance and direction from start to finish. “ Displacement” A B d or Δd Does not depend on path taken, only start and finish Δd Definition of displacement: change of position

19 More Kinematics Quantities Tells us where something is relative to some given reference point

20 More Kinematics Quantities Tells us where something is relative to some given reference point Position

21 More Kinematics Quantities Tells us where something is relative to some given reference point Position Definition: straight line distance and direction of something relative to a reference point

22 More Kinematics Quantities Tells us where something is relative to some given reference point Position Definition: straight line distance and direction of something relative to a reference point Symbol: ???

23 More Kinematics Quantities Tells us where something is relative to some given reference point Position Definition: straight line distance and direction of something relative to a reference point Symbol: d

24 Position Example State the position of the stick man relative to the school. School N E 32º 53 m d =??

25 Position Example State the position of the stick man relative to the school. School N E 32º 53 m d = 53 m [E32°S] or [S58°E]

26 Comparison of Position and Displacement Position Displacement

27 Comparison of Position and Displacement Position vector Displacement vector

28 Comparison of Position and Displacement Position vector Straight line distance and direction of something from a given reference point Displacement vector

29 Comparison of Position and Displacement Position vector Straight line distance and direction of something from a given reference point Displacement vector Straight line distance and direction from a starting position to a finishing position

30 Comparison of Position and Displacement Position vector Straight line distance and direction of something from a given reference point Involves where something is at one instant in time Displacement vector Straight line distance and direction from a starting position to a finishing position

31 Comparison of Position and Displacement Position vector Straight line distance and direction of something from a given reference point Involves where something is at one instant in time Displacement vector Straight line distance and direction from a starting position to a finishing position Involves a definite interval of time with a starting time and a separate finishing time

32 Speed Definition: ????

33 Speed Definition: rate of change of distance or change- in distance over change-in time

34 Speed Definition: rate of change of distance or change- in distance over change-in time Defining Equation: ?????

35 Speed Definition: rate of change of distance or change- in distance over change-in time Defining Equation: V = Δd/Δt Symbol for speed

36 Speed Definition: rate of change of distance or change- in distance over change-in time Defining Equation: Units: ????? V = Δd/Δt Symbol for speed

37 Speed Definition: rate of change of distance or change- in distance over change-in time Defining Equation: Units: m/s km/h miles/h cm/s V = Δd/Δt Symbol for speed

38 Two kinds of Speed: Average and Instantaneous Average SpeedInstantaneous Speed

39 Two kinds of Speed: Average and Instantaneous Average Speed Use formula v=Δd/Δt Instantaneous Speed Use formula v=Δd/Δt

40 Two kinds of Speed: Average and Instantaneous Average Speed Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Instantaneous Speed Use formula v=Δd/Δt

41 Two kinds of Speed: Average and Instantaneous Average Speed Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Instantaneous Speed Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t

42 Two kinds of Speed: Average and Instantaneous Average Speed Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Slope of secant line of d vs t graph Instantaneous Speed Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t

43 Two kinds of Speed: Average and Instantaneous Average Speed Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Slope of secant line of d vs t graph Instantaneous Speed Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t Slope of tangent line of d vs t graph

44 Velocity Definition: ????

45 Velocity Definition: rate of change of position or change-in position over change-in time

46 Velocity Definition: rate of change of position or change-in position over change-in time Defining Equation: ????

47 Velocity Definition: rate of change of position or change-in position over change-in time Defining Equation: V = Δd/Δt velocity Change-in position or displacement

48 Velocity Definition: rate of change of position or change-in position over change-in time Defining Equation: V = Δd/Δt Units: ????? velocity Change-in position or displacement

49 Velocity Definition: rate of change of position or change-in position over change-in time Defining Equation: V = Δd/Δt Units: m/s km/h m/s cm/min velocity Change-in position or displacement

50 Two kinds of Velocity: Average and Instantaneous Average Velocity Instantaneous Velocity

51 Two kinds of Velocity: Average and Instantaneous Average Velocity Use formula v=Δd/Δt Instantaneous Velocity Use formula v=Δd/Δt

52 Two kinds of Velocity: Average and Instantaneous Average Velocity Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Instantaneous Velocity Use formula v=Δd/Δt

53 Two kinds of Velocity: Average and Instantaneous Average Velocity Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Instantaneous Velocity Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t

54 Two kinds of Velocity: Average and Instantaneous Average Velocity Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Slope of secant line of d vs t graph Instantaneous Velocity Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t

55 Two kinds of Velocity: Average and Instantaneous Average Velocity Use formula v=Δd/Δt Always involves a definite time interval with a distinct initial time t 1 and distinct final time t 2 so Δt = t 2 -t 1 ≠ 0 Slope of secant line of d vs t graph Instantaneous Velocity Use formula v=Δd/Δt Δt = t 2 -t 1 is so small that the initial time t 1 is infinitesimally close to t 2, therefore v ins occurs at one instant t 1 = t 2 = t Slope of tangent line of d vs t graph

56 Acceleration Definition: ??????

57 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time

58 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time Defining Equation: ???????

59 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time Defining Equation: a =Δv/Δt = ???? acceleration Change-in velocity

60 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time Defining Equation: a =Δv/Δt = (v 2 – v 1 )/Δt acceleration Change-in velocity Final velocity Initial velocity

61 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time Defining Equation: a =Δv/Δt = (v 2 – v 1 )/Δt equations can be used for constant, average and instantaneous accelerations acceleration Change-in velocity Final velocity Initial velocity

62 Acceleration Definition: rate of change of velocity or change-in velocity over change-in time Defining Equation: a =Δv/Δt = (v 2 – v 1 )/Δt equations can be used for constant, average and instantaneous accelerations Units: m/s/s or m/s 2 or (km/h)/s and more acceleration Change-in velocity Final velocity Initial velocity

63 Three forms or Ways to get Acceleration To get an acceleration, we need a change-in velocity. In what ways can the velocity vector change?

64 Three forms or Ways to get Acceleration To get an acceleration, we need a change-in velocity. In what ways can the velocity vector change? 1.Speeding up... velocity vector increases in length when acceleration vector is oriented in same direction as initial velocity v1v1 a

65 Three forms or Ways to get Acceleration To get an acceleration, we need a change-in velocity. In what ways can the velocity vector change? 1.Speeding up... velocity vector increases in length when acceleration vector is oriented in same direction as initial velocity 2.Deceleration... Velocity vector decreases in length when acceleration vector is opposite direction as v 1 (slowing down) v1v1 a v1v1 a

66 Three forms or Ways to get Acceleration To get an acceleration, we need a change-in velocity. In what ways can the velocity vector change? 3.Changing direction... velocity vector changes direction but not magnitude or length when the acceleration vector is 90° to the initial velocity v1v1 a

67 Three forms or Ways to get Acceleration To get an acceleration, we need a change-in velocity. In what ways can the velocity vector change? 3.Changing direction... velocity vector changes direction but not magnitude or length when the acceleration vector is 90° to the initial velocity v1v1 a

68 Constant Acceleration

69 If the velocity changes by the same amount during equal time intervals

70 Constant Acceleration If the velocity changes by the same amount during equal time intervals Example: acceleration of projectiles near the earth's surface where air friction is negligible

71 Constant Acceleration If the velocity changes by the same amount during equal time intervals Example: acceleration of projectiles near the earth's surface where air friction is negligible a g = g = 9.80 m/s 2 [down] or ≈ 10.0 m/s 2 [down]

72 Constant Acceleration If the velocity changes by the same amount during equal time intervals Example: acceleration of projectiles near the earth's surface where air friction is negligible a g = g = 9.80 m/s 2 [down] or ≈ 10.0 m/s 2 [down] Meaning: ????????

73 Constant Acceleration If the velocity changes by the same amount during equal time intervals Example: acceleration of projectiles near the earth's surface where air friction is negligible a g = g = 9.80 m/s 2 [down] or ≈ 10.0 m/s 2 [down] Meaning: Every second, the velocity changes by 10.0 m/s [down]

74 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 Instantaneous Velocity (meters/second) 30.0 [up] ?

75 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up]

76 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] ?

77 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up]

78 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] ?

79 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] 0.00

80 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 4.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] 0.00 ?

81 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 4.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] 0.00 10.0 [down]

82 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 4.00 5.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] 0.00 10.0 [down] ?

83 Constant Acceleration Example: projectile fired upward at 30.0 m/s Time (seconds) 0.00 1.00 2.00 3.00 4.00 5.00 Instantaneous Velocity (meters/second) 30.0 [up] 20.0 [up] 10.0 [up] 0.00 10.0 [down] 20.0 [down]

84 Deriving the Big Five Constant Acceleration Formulas

85 (1) Acceleration in terms of v 1, v 2 and Δt: a = ????

86 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) Δt

87 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt

88 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt Multiply both sides of #1a by Δt :

89 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt Multiply both sides of #1a by Δt : Δt a = (v 2 - v 1 )

90 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt Multiply both sides of #1a by Δt : Δt a = (v 2 - v 1 ) Divide both sides by a :

91 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt Multiply both sides of #1a by Δt : Δt a = (v 2 - v 1 ) Divide both sides by a : Δt = (v 2 - v 1 ) a

92 Deriving the Big Five Constant Acceleration Formulas (1) Acceleration in terms of v 1, v 2 and Δt: a = (v 2 - v 1 ) We will call this BIG FIVE #1a Δt Multiply both sides of #1a by Δt : Δt a = (v 2 - v 1 ) Divide both sides by a : Δt = (v 2 - v 1 ) We will call this BIG FIVE #1b a

93 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt:

94 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 )

95 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 ) Reverse left and right sides: (mathematically legal)

96 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 ) Reverse left and right sides: (mathematically legal) v 2 - v 1 = Δt a

97 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 ) Reverse left and right sides: (mathematically legal) v 2 - v 1 = Δt a Solve for v 2

98 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 ) Reverse left and right sides: (mathematically legal) v 2 - v 1 = Δt a Solve for v 2 v 2 = v 1 + Δt a

99 Deriving the Big Five Constant Acceleration Formulas (1) One more formula with acceleration in terms of v 1, v 2 and Δt: From the previous slide we have: Δt a = (v 2 - v 1 ) Reverse left and right sides: (mathematically legal) v 2 - v 1 = Δt a Solve for v 2 v 2 = v 1 + Δt a We will call this BIG FIVE #1c

100 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt:

101 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ?

102 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt

103 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ?

104 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ? The above formula can be modified for a ≠ 0. How?

105 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ? The above formula can be modified for a ≠ 0. How? Δd = v avg Δt

106 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ? The above formula can be modified for a ≠ 0. How? Δd = v avg Δt What is v avg in terms of v 1 and v 2 ?

107 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ? The above formula can be modified for a ≠ 0. How? Δd = v avg Δt What is v avg in terms of v 1 and v 2 ? Δd = (v 1 + v 2 ) Δt 2

108 Deriving the Big Five Constant Acceleration Formulas (2) Displacement Δd in terms of v 1, v 2, and Δt: If an object moves at a constant velocity v for Δt, what formula gives us Δd ? Δd = v Δt Why can't this formula be used for acceleration ≠ 0 ? The above formula can be modified for a ≠ 0. How? Δd = v avg Δt What is v avg in terms of v 1 and v 2 ? Δd = (v 1 + v 2 ) Δt We will call this BIG FIVE #2 2

109 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a

110 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2:

111 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2

112 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2:

113 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2: Δd = (v 1 + v 1 + Δt a ) Δt 2

114 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2: Δd = (v 1 + v 1 + Δt a ) Δt ?????? 2

115 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2: Δd = (v 1 + v 1 + Δt a ) Δt Δd = (2v 1 + Δt a ) Δt 2 2

116 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2: Δd = (v 1 + v 1 + Δt a ) Δt Δd = (2v 1 + Δt a ) Δt 2 2 Expand and simplify:

117 Deriving the Big Five Constant Acceleration Formulas (3) Displacement Δd in terms of v 1, Δt and a Here are BIG FIVE equations #1c and #2: v 2 = v 1 + Δt a #1c Δd = (v 1 + v 2 ) Δt #2 2 Without simplifying, substitute #1c into #2: Δd = (v 1 + v 1 + Δt a ) Δt Δd = (2v 1 + Δt a ) Δt 2 2 Expand and simplify: Δd = v 1 Δt + a Δt 2 /2 We will call this BIG FIVE equation #3

118 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a

119 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2

120 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 ???????

121 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 Δd = (v 1 + v 2 )(v 2 - v 1 ) 2 a

122 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 Δd = (v 1 + v 2 )(v 2 - v 1 ) Δd = (v 2 + v 1 )(v 2 - v 1 ) 2 a 2 a

123 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 Δd = (v 1 + v 2 )(v 2 - v 1 ) Δd = (v 2 + v 1 )(v 2 - v 1 ) 2 a 2 a

124 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 Δd = (v 1 + v 2 )(v 2 - v 1 ) Δd = (v 2 + v 1 )(v 2 - v 1 ) 2 a 2 a Δd = (v 2 2 – v 1 2 ) 2 a

125 Deriving the Big Five Constant Acceleration Formulas (4) Displacement Δd in terms of v 1, v 2 and a Here are BIG FIVE equations #1b and #2: Δt = (v 2 - v 1 ) #1b Δd = (v 1 + v 2 ) Δt #2 a 2 Substitute #1b into #2 Δd = (v 1 + v 2 )(v 2 - v 1 ) Δd = (v 2 + v 1 )(v 2 - v 1 ) 2 a 2 a Δd = (v 2 2 – v 1 2 ) 2 a We will call this BIG FIVE Equation #4

126 Big Five equation #5 Homework Exercise: Derive the fifth Big Five equation using one form equation #1 and equation #2. This equation is: Δ d = v 2 Δt - a Δt 2 /2

127 List of BIG FIVE equations Memorize these please!! (#1a) a = (v 2 - v 1 ) (#1b) Δt = (v 2 - v 1 ) Δt a (#1c) v 2 = v 1 + Δt a (#2) Δd = (v 1 + v 2 ) Δt (#3) Δd = v 1 Δt + a Δt 2 /2 2 (#4) Δd = (v 2 2 – v 1 2 ) or (#4b) v 2 2 – v 1 2 = 2aΔd 2a (#5) Δ d = v 2 Δt - a Δt 2 /2

128 When can we use the BIG FIVE? Only for constant non-zero acceleration

129 When can we use the BIG FIVE? Only for constant non-zero acceleration Note: Vector quantities cannot be multiplied together. Some of the BIG FIVE equations appear to break this rule. However, if the motion analyzed is along a line in one dimension, we can get away with multiplying vectors by representing them as + or – integers.

130 When can we use the BIG FIVE? Only for constant non-zero acceleration Note: Vector quantities cannot be multiplied together. Some of the BIG FIVE equations appear to break this rule. However, if the motion analyzed is along a line in one dimension, we can get away with multiplying vectors by representing them as + or – integers. Example: 2aΔd = 2(10.0 m/s 2 [down])(2.5 m [up]) = ?????

131 When can we use the BIG FIVE? Only for constant non-zero acceleration Note: Vector quantities cannot be multiplied together. Some of the BIG FIVE equations appear to break this rule. However, if the motion analyzed is along a line in one dimension, we can get away with multiplying vectors by representing them as + or – integers. Example: 2aΔd = 2(10.0 m/s 2 [down])(2.5 m [up]) = 2(-10)(+2.5)

132 When can we use the BIG FIVE? Only for constant non-zero acceleration Note: Vector quantities cannot be multiplied together. Some of the BIG FIVE equations appear to break this rule. However, if the motion analyzed is along a line in one dimension, we can get away with multiplying vectors by representing them as + or – integers. Example: 2aΔd = 2(10.0 m/s 2 [down])(2.5 m [up]) = 2(-10)(+2.5) = -50 = ?????

133 When can we use the BIG FIVE? Only for constant non-zero acceleration Note: Vector quantities cannot be multiplied together. Some of the BIG FIVE equations appear to break this rule. However, if the motion analyzed is along a line in one dimension, we can get away with multiplying vectors by representing them as + or – integers. Example: 2aΔd = 2(10.0 m/s 2 [down])(2.5 m [up]) = 2(-10)(+2.5) = -50 = 50 m 2 /s 2 [down]

134 What equations do we use for a =0 ?

135 If the acceleration is zero, how do we describe the motion?

136 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity

137 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ?

138 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt

139 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt This is called the LITTLE ONE!!

140 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt Note there are two other forms of this same equation. What are they?

141 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt Note there are two other forms of this same equation. What are they? Δt = Δd/v and v = Δd/Δt

142 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt Note there are two other forms of this same equation. What are they? Δt = Δd/v and v = Δd/Δt Δd v Δt

143 What equations do we use for a =0 ? If the acceleration is zero, how do we describe the motion? a =0 means constant velocity There is only one equation that describes motion at a constant velocity. What is it ? Δd = v Δt Note there are two other forms of this same equation. What are they? Δt = Δd/v and v = Δd/ΔtΔd Again we call this the LITTLE one! v Δt


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