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Physics Beyond 2000 Chapter 1 Kinematics.

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Presentation on theme: "Physics Beyond 2000 Chapter 1 Kinematics."— Presentation transcript:

1 Physics Beyond 2000 Chapter 1 Kinematics

2 Physical Quantities Fundamental quantities Derived quantities

3 Fundamental Quantities
Quantity Symbol SI Unit Mass m kg Length l Time t s Others -

4 Derived Quantities Can be expressed in terms of the basic quantities
Examples Velocity Example 1 Any suggestions?

5 Derived Quantities More examples

6 Standard Prefixes Use prefixes for large and small numbers Table 1-3
Commonly used prefixes giga, mega, kilo centi, milli, micro, nana, pico

7 Significant Figures The number of digits between the Most significant figure and least significant figure inclusive. The leftmost non-zero digit is the most significant figure. If there is no decimal point, the rightmost non-zero digit will be the least significant figure. If there is a decimal point, the rightmost digit is always the least significant figure.

8 Scientific Notation Can indicate the number of significant numbers

9 Significant Figures Examples 5 and 6. See if you understand them.

10 Significant Figures Multiplication or division.
The least number of significant figures. Addition or subtraction. The smallest number of significant digits on the right side of the decimal point.

11 Order of Magnitude Table 1-4.

12 Measurement Practice Length Meter rule Vernier caliper
Micrometer screw gauge Practice

13 Measurement Time interval Stop watch Ticker tape timer Timer scaler

14 Measurement Mass Triple beam balance Electronic balance

15 Measurement Computer data logging

16 Error Treatment Personal errors Random errors System errors
Personal bias Random errors Poor sensitivity of the apparatus System errors Measuring instruments Techniques

17 Accuracy and Precision
How close the measurement to the true value Precision Agreement among repeated measurements Largest probable error tells the precision of the measurement

18 Accuracy and Precision
Examples 9 and 10

19 Accuracy and Precision
Sum and difference The largest probable error is the sum of the probable errors of all the quantities. Example 11

20 Accuracy and Precision
Product, quotient and power Derivatives needed

21 Kinematics Distance d Displacement s

22 Average Velocity Average velocity = displacement  time taken

23 Instantaneous Velocity
Rate of change of displacement in a very short time interval.

24 Uniform Velocity Average velocity = Instantaneous velocity when the velocity is uniform.

25 Speed Average speed Instantaneous speed

26 Speed and Velocity Example 13

27 Relative Velocity The velocity of A relative to B
The velocity of B relative to A

28 Relative Velocity Example 14

29 Acceleration Average acceleration Instantaneous acceleration

30 Average acceleration Example 15 Average acceleration =
change in velocity  time Example 15

31 Instantaneous acceleration
Example 16

32 Velocity-time graph v-t graph
Slope: = acceleration

33 v-t graph Uniform velocity: slope = 0 v t

34 v-t graph Uniform acceleration: slope = constant v t

35 Falling in viscous liquid
Acceleration Uniform velocity

36 Falling in viscous liquid
uniform speed: slope = 0 acceleration: slope=g at t=0 t

37 Bouncing ball with energy loss
Let upward vector quantities be positive. Falling: with uniform acceleration a = -g.

38 v-t graph of a bouncing ball
Uniform acceleration: slope = -g v t falling

39 Bouncing ball with energy loss
Let upward vector quantities be positive. Rebound: with large acceleration a.

40 v-t graph of a bouncing ball
Large acceleration on rebound v rebound t falling

41 Bouncing ball with energy loss
Let upward vector quantities be positive. Rising: with uniform acceleration a = -g.

42 v-t graph of a bouncing ball
Uniform acceleration: slope = -g v rebound rising t falling

43 v-t graph of a bouncing ball
The speed is less after rebound falling and rising have the same acceleration: slope = -g v rebound rising t falling

44 Linear Motion: Motion along a straight line
Uniformly accelerated motion: a = constant velocity v u time t

45 Uniformly accelerated motion
u = initial velocity (velocity at time = 0). v = final velocity (velocity at time = t). a = acceleration v = u + at

46 Uniformly accelerated motion
= average velocity velocity v u time t

47 Uniformly accelerated motion
s = displacement = velocity v u time t s = area below the graph

48 Equations of uniformly accelerated motion

49 Uniformly accelerated motion
Example 17

50 Free falling: uniformly accelerated motion
Let downward vector quantities be negative a = -g

51 Free falling: uniformly accelerated motion
a = -g

52 Free falling: uniformly accelerated motion
Example 18

53 Parabolic Motion Two dimensional motion under constant acceleration.
There is acceleration perpendicular to the initial velocity Examples: Projectile motion under gravity. Electron moves into a uniform electric field.

54 Monkey and Hunter Experiment
electromagnet gun aluminium foil bullet iron ball

55 Monkey and Hunter Experiment
electromagnet gun aluminium foil bullet iron ball The bullet breaks the aluminium foil.

56 Monkey and Hunter Experiment
electromagnet gun bullet iron ball Bullet moves under gravity. Iron ball begins to drop.

57 Monkey and Hunter Experiment
electromagnet gun bullet Bullet is moving under gravity. Iron ball is dropping under gravity.

58 Monkey and Hunter Experiment
electromagnet gun

59 Monkey and Hunter Experiment
electromagnet gun The bullet hits the ball!

60 Monkey and Hunter Experiment
The vertical motions of both the bullet and the iron are the same. The vertical motion of the bullet is independent of its horizontal motion.

61 Projectile trajectory
x

62 Projectile trajectory
x

63 Projectile trajectory
u x u = initial velocity  = initial angle of inclination

64 Projectile trajectory
v Horizontal line u x v = velocity at time t  = angle of velocity to the horizontal at time t

65 Projectile trajectory
u x = x-component of u = y-component of u

66 Projectile trajectory
u x

67 Projectile trajectory: accelerations
u x

68 Projectile trajectory
v Horizontal line u vertical line x = x-component of v = y-component of v

69 Projectile trajectory: velocity in horizontal direction
Horizontal line u x

70 Projectile trajectory: velocity in vertical direction
Horizontal line u vertical line x

71 Projectile trajectory: displacement
s = displacement y s x x = x-component of s y = y-component of s

72 Projectile trajectory: horizontal displacement
s = displacement y s x

73 Projectile trajectory: vertical displacement
s = displacement y s x

74 Equation of trajectory: a parabolic path
s = displacement y s x

75 Projectile trajectory: direction of motion
v Horizontal line u vertical line Projectile trajectory x Angle  represents the direction of motion at time t.

76 Projectile trajectory: direction of motion
v Horizontal line u vertical line Projectile trajectory x

77 Projectile trajectory
Example 19

78 Projectile trajectory: maximum height H
x At H, = 0

79 Projectile trajectory: range R
u R x At R, y = 0

80 Projectile trajectory: maximum range Rmax
Rmax x is maximum when

81 Projectile trajectory: maximum range Rmax
Rmax x R is maximum when

82 Projectile trajectory: maximum range Rmax
Rmax x

83 Projectile trajectory: time of flight to
u to R x At time= to , y = 0

84 Projectile trajectory: two angles for one range
u u 2 1 R x 1= 2


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