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PASS Content Standard 2.1 Objects change their motion only when

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Presentation on theme: "PASS Content Standard 2.1 Objects change their motion only when"— Presentation transcript:

1 PASS Content Standard 2.1 Objects change their motion only when
a net force is applied. Laws of motion are used to determine the effects of forces on the motion of objects.

2 What is motion?

3 Motion is a change in position, measured by distance and time

4 Motion - 12 min

5 A reference point is needed to measure movement

6 Are you moving right now?

7 What is your reference point?

8 Earth rotates on its axis at 1,100 mph Earth orbits the Sun at 68,000 mph

9 The whole galaxy rotates
at 490,000 mph

10 Frames of Reference

11 Frames of Reference

12 Two Dimensional World

13 Speed is the distance traveled by a moving object over a period of time

14 Speed - 4 min

15 distance Speed = time

16 distance Speed = time 10 feet = = 2 feet/min 5 minutes
A snail crawls 10 feet in 5 minutes. What is the speed of the snail? distance Speed = time 10 feet = = 2 feet/min 5 minutes

17 object is not always constant
The speed of a moving object is not always constant

18 total distance Average speed = total time

19 total distance Average speed = total time 1 mile + 1 mile 2 miles = =
A boy runs 1 mile in 6 minutes, rests for 2 minutes, then walks 1 mile in 12 minutes. What is his average speed? total distance Average speed = total time 1 mile + 1 mile 2 miles = = 20 minutes 20 minutes

20 Speed Calcaulation Practice

21 Graphing Speed Distance (meters) Time (seconds)

22 Velocity is speed in a given direction

23 Velocity is a vector quantity because it has both speed and direction.

24 Vectors - 12 min

25 All these planes have the same speed. How is their velocity different?

26 Vector Addition The length of the line represents the quantity (speed) and the arrow indicates the direction. Add vectors head to tail.

27 Vector Addition Direction is indicated by compass degrees

28 The magnitude of the speed is indicated by the measured length (scale)
Vector Addition The magnitude of the speed is indicated by the measured length (scale) of the line.

29 Vector Addition

30 is the velocity of the plane?
An airplane is flying 200 mph at 50o. Wind velocity is 50 mph at 270o. What is the velocity of the plane? 180o 0o 270o

31 90o 180o 0o 270o

32 90o 180o 0o 270o

33 90o 180o 0o 270o

34 90o 180o 0o 270o

35 90o 180o 0o 270o

36 Practice Vector Addition

37 Acceleration

38 Acceleration is the rate of change of velocity

39 Velocity(final) - Velocity(original)
Acceleration = time

40 A car traveling at 60 mph accelerates to
90 mph in 3 seconds. What is the car’s acceleration? Velocity(final) - Velocity(original) Acceleration = time 90 mph - 60 mph = 3 seconds 30 mph = 3 seconds = 10 mph/second

41 There is no such thing as Deceleration

42 A car traveling at 60 mph slams on the breaks to
avoid hitting a deer. The car comes to a safe stop 6 seconds after applying the breaks. What is the car’s acceleration? Velocity(final) - Velocity(original) Acceleration = time 0 mph - 60 mph = 6 seconds - 60 mph = 6 seconds = - 10 miles per hour per second

43 Acceleration Calcaulation Practice

44

45 Centripetal Acceleration
Acceleration toward the center of a circular path.

46 Centripetal Acceleration
For an object to travel in a curved path, some force must be accelerating it toward the center of the circle.

47 Centripetal Acceleration

48 Force provided by engine Acceleration provided by tires

49 Centripetal Acceleration
What happens if the accelerating force is removed?

50 An apparent force that appears only in rotating frames of reference.
Centrifugal Force An apparent force that appears only in rotating frames of reference.

51 This “false” force appears to push away from the center of the
Centrifugal Force This “false” force appears to push away from the center of the circular path.

52 Forces cause changes in motion

53 Aristotle and Newton had different ideas about forces and motion.
Aristotle's idea: For an object to move at a constant speed, a constant force must be applied. Newton's idea: An object moving at a constant speed will continue at that speed without additional force being applied.

54 Force Any Push Or Pull

55 Forces & motion - 6 min

56 Balanced Forces Produce NO Motion

57 Unbalanced Forces Produce Motion

58 A force that opposes motion
Friction A force that opposes motion

59 Types of Friction Sliding - two solid surfaces rubbing
against each other. Rolling - an object rolling over a surface. Fluid - an object moving through a fluid.

60 Newton's Laws

61 Newton’s Laws - 5 min

62 First Law of Motion An object at rest will remain at rest, and a
moving object will remain at a constant velocity unless acted on by unbalanced forces.

63 Second Law of Motion F = Ma Force = mass X acceleration

64 For every action, there is an equal and opposite reaction. Third Law
of Motion For every action, there is an equal and opposite reaction.

65 Rockets - 6 min

66 Momentum mass X velocity

67 Momentum mass X velocity

68 Momentum - 8 min

69 Does a long pendulum swing faster than a short one?

70 Does a heavy pendulum swing faster than a light one?

71 Momentum is the same before and after a collision

72 Conservation of Momentum
The total momentum of any group of objects remains the same unless acted on by outside forces.

73 Collisions Elastic - occur when both momentum and kinetic energy are conserved. Inelastic - occur when momentum is conserved, but kinetic energy is not.

74 Collisions M1V1 = M2V2 Before After

75 Colliding objects have same mass
Elastic Collision

76 Heavy object strikes light object
Elastic Collision

77 Light object strikes heavy object
Elastic Collision

78 Colliding objects have same mass
Inelastic Collision

79 Rollercoasters work because of momentum

80 Rollercoaster Physics

81 Rollercoasters - 24 min

82 Is work being done?

83

84 Units of Force are Newtons Units of Distance are Meters
Work = F d Units of Force are Newtons Units of Distance are Meters Newton Meters = Joules

85 Units of Work are Joules
Power is the rate at which work is done. Power = work / time Units of Work are Joules Joules per second = Watts

86 Work & Power - 15 min

87 power - 2 min

88 1 Horsepower is equal to Watts or 550 ft lb/sec

89 Work & Power Calcaulation Practice

90 Bus

91 Machines make work easier

92 Machines make work easier by changing the size or direction of a force

93 Climbing cars - 24 min

94 2 forces are related to machines

95 The effort force is applied to a machine. 2 forces are related
to machines The effort force is applied to a machine.

96 The resistance force is applied by a machine.
2 forces are related to machines The resistance force is applied by a machine.

97 The number of times a machine multiplies the effort force.
Mechanical Advantage The number of times a machine multiplies the effort force.

98 Work output Work input X 100
Efficiency % Work output Work input X 100

99 Inventors

100 Da Vinci - 8 min

101 Simple Machines

102 Do work with one motion Simple Machines

103 6 Simple MachineS Inclined Plane Lever Pulley Wedge Screw Wheel & Axle

104 Work is made easier because
the effort force moves over a greater distance.

105 Inclined Plane - 2 min

106 Force is multiplied since it is
applied to a wide area and exerted over a small area.

107 Wedge - 2 min

108 Multiplies an effort force
by acting through a long effort distance.

109 Screw - 1 min

110 A bar which can move freely around a fixed position, or fulcrum.

111 Levers - 3 min

112 The Fulcrum is between the Effort Force and the Resistance force

113 Multiplies Effort Force and
changes its direction

114 The Resistance is between the Effort Force and the Fulcrum

115 Multiplies the Effort Force but
does not change its direction

116 The Effort force is between the Resistance Force and the Fulcrum

117 Does not multiply the Effort Force

118 Types of Pulleys Fixed Movable

119 Single Fixed Pulley Direction of the Effort Force is changed. Mechanical Advantage = 0

120 Single Movable Pulley Direction of the Effort Force is not changed. Mechanical Advantage = 1

121 Direction of the Effort Force is changed.
Pulley System Direction of the Effort Force is changed. Mechanical Advantage is equal to the number of supporting ropes.

122 Pulleys - 1 min

123 A fixed pulley does not have a mechanical advantage. Fixed pulleys only change the direction of the force.

124 A movable pulley does have a mechanical advantage. The effort force is in the direction of the movement of the resistance.

125 Two wheels of different sizes
connected - the axle being the smaller wheel.

126 Wheel & Axle - 1 min

127 Worm Gear

128 Compound Machines

129 Simple Machine Combinations

130 Compound Machines - 4 min

131 Rube Goldberg Device

132 Rube Goldberg Device

133 Rube Goldberg Device

134 Rube Goldberg Device

135 Rube Goldberg Device

136 END Content Standard 2.1


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