phy 3.1.notebook September 19, 2017 Everything Moves

Transcription

1 Eerything Moes 1

2 2

3 \ Diagrams: Motion 1) Motion (picture) no reference! time lapsed photo Type Motion? 3

4 origin Diagrams: reference pt. Motion reference! 1) Motion (picture) diagram time lapsed photo by inserting lines on the wall in the background you hae a "reference point" to compare the motion of the runner 4

5 Diagrams: origin reference pt. Motion reference alues 1) Motion (picture) diagram time lapsed photo A = 1 cm B =.9 cm C =.4 cm D = +.2 cm E = +.5 cm by inserting lines on the wall in the background you hae a "reference point" to compare the motion of the runner displacement A B C D E 5

6 2) Particle Model sometimes easier to see what's happening because it reduces the object to a point source and eliminates outside distractions What are the four types of motion? a Particle/Point model: when the size of the object is much less than the dist. it moes! when you can ignore the internal motions c How would a graph look????? 6

7 . y D i5 s4 t3 a 2 n 1 c e Time x 7

8 a) D i s 9 t 8a 7n 6c e y Time x

9 y 10 D i s t a n c e b).... x Time 9

10 y 10 9 c) D i s t a n c e x Time 10

11 . y 10 9 d) D i s t a n c e x Time 11

12 Little Andy rolls a ball along the ground 1) motion along the "x" axis origin Andy has arm problems! origin distance: 1 m 1 m displacement: 1 m,+ 1 m scalar tell size only ector tells size and direction 12

13 Little Andy rolls a ball along the ground 1) motion along the "x" axis using ectors to represent motion! 4.0 m Andy has arm problems! origin origin a d scale 1 cm = 0.5 m 13

14 little Andy drops a rock Andy still has arm problems!." " 1) motion along the "y" axis a) what will the particle diagram look like? b) what will the ectors look like? using ectors to represent motion! 14

15 little Andy drops a rock 1) motion along the "y" axis Andy still has arm problems! a) what will the particle diagram look like? b) what will the ectors look like? using ectors to represent motion! 15

16 little Andy drops a rock 1) motion along the "y" axis Andy still has arm problems! a) what will the particle diagram look like? b) what will the ectors look like? using ectors to represent motion! 16

17 little Andy drops a rock. 1) motion along the "y" axis a Andy still has arm problems! d a) what will the particle diagram look like? b) what will the ectors look like? using ectors to represent motion! a " " stands for aerage elocity why aerage elocity in this situation? 17

18 see Andy putt! using ectors to represent motion! Andy makes the most of his arm problems! 18

19 d phy 3.1.notebook see Andy putt! using ectors to represent motion! Andy makes the most of his arm problems!. a a a 19

20 little Andy drops a rock Here's where we're going! Andy doesn't care anymore! d = 1.88 m THE STEPS!!!!! 1) Data/diagrams? gien and understood particle and/or ector diagram 2) Type motion? rest/constant elocity, acceleration (arying el,) t = 0.63 s 3) Formulas that apply? to come later! 20

21 Motion: rest Constant elocity arying elocity acceleration _ = Δd/t = Δd t /t _ = ( )/2 the " " is critical!!!!!!!!!!!!! Note the difference between Δ and a = Δ/t a = ( 2 1 )/t 21

22 little Andy drops a rock. origin 1) Data? a Andy still has arm problems! d 2) Type motion? 3) Formulas that apply? t = 0.63 s 2 =? a d = 1.88 m 22

23 little Andy drops a rock a Andy still has arm problems! t = 0.63 s 2 =? a. d = 1.88 m d d = 1.88 m 1) Data? origin 1 = 0 2) Type motion? t = 0.63 s a (g) = 9.8 m/s 2 _ or, a 3) Formulas that apply? _ = _ = Δd t /t a = Δ/t 23

24 1 = 0 Δd = 1.88 m Δt = 0.63 s 1 = 0, 2 =? 2 =? a _ = d t /t t = 1.88 m/0.63 s = 3.0 m/s where is that? _ = ( ) 2 _ 2 = = 2( 3.0 m/s) 0 2 = 6.0 m/s a = Δ/t = ( 2 1 )/t a = ( 6.0 m/s 0)/0.63 s a = 9.5 m/s 2 m/s s ( m/s m/s m/s 1 s s ( 1 s ( s = = = = m/s s 1 s ( ( ( 24

25 formulas for arying elocity _ d = d t /t t = t t = d/ t _ = ( )/2 _ 2 = 2 1 _ 1 = 2 2 a = Δ/t = ( 2 1 )/t 2 = 1 + at 1 = 2 at t = ( 2 1 )/a 25

26 m t = 1.68s m A ball starts from rest and rolls down a ramp, what elocity does it attain at the bottom?...what is its acceleration? 1) Data/diagram? 2) Type Motion? 3) Formulas that apply? 26

27 . a a d d ll means parallel to motion m m t = 1.68 s 1) Data? 2) Type Motion? d ll = m d h = m t = 1.68 s 1 = 0 3) Formulas that apply? = a = t = d t 27

28 d ll = m m m t = 1.68 s 1) Data? 2) Type Motion? d ll = m d h = m t = 1.68 s 1 = 0 3) Formulas that apply? = d t = a = 2 t a = 2 1 t a = 1.40 m/s s a = m/s 2 = d t m = 1.68 s = m/s = = = 2(.699 m/s) 0 2 = 1.40 m/s 28

29 . Little Andy throws a rock. It leaes his hand at 12 m/s and traels for 3.0 seconds. How far does it go? 29

30 ..... d. a = 12 m/s t = 3.0 s d =? Little Andy throws a rock. It leaes his hand at 12 m/s and traels for 3.0 seconds. How far does it go? 30

31 ..... d. a = 12 m/s t = 3.0 s d =? TM? constant Little Andy throws a rock. It leaes his hand at 12 m/s and traels for 3.0 seconds. How far does it go? 31

32 a Little Andy throws a rock. It leaes his hand at 12 m/s and traels for 3.0 seconds. How far does it go? d = 12 m/s t = 3.0 s d =? TM? constant... = d/t d = t d = 12 m/s(3.0 s) d = 36 m m = m/s (s) 32

33 A 955 kg car slows from 55 mph to 35 mph in 1.3 s. What is the deceleration? How far did he trael during the decelerating? data? 33

34 1 = 55 mph 2 = 35 mph A 955 kg car slows from 55 mph to 35 mph in 1.3 s. What is the deceleration? How far did he trael during the decelerating? t = 1.3 s a =? d =? particle diagram/ectors? 34

35 d phy 3.1.notebook 1 = 55 mph 2 = 35 mph..... t = 1.3 s a =? d =? a a 35

36 1 = 55 mph 2 = 35 mph t = 1.3 s a =? d =? 25 m/s conert 16 m/s a = Δ/t = ( 2 1 )/t a = (16 m/s 25 m/s)/1.3 s a = 6.9 m/s/s = 6.9 m/s 2 55 miles/hr(1 hr/3600s)(1610 m/1mile) = 25 m/s 35 miles/hr(1 hr/3600s)(1610 m/1mile) = 16 m/s = d t /t t ( d t = t = t ( d t = 25 m/s + 16 m/s 2 d t = 27 m ( ( 1.3 s 36

37 A little girl drops a rock from rest and it hits the ground 0.46 s later. What elocity does it hit the ground at? t = 0.46 s ectors? 1 = 0 2 =? 37

38 d a a phy 3.1.notebook. t = 0.46 s 1 = 0 2 =? anything else known? 38

39 t = 0.46 s 1 = 0 2 =? a = 9.8 m/s 2 TM? a,... a = Δ/t... _ = _ = Δd t /t a = Δ/t you hae "a" and "t" and want 2 2 = 1 + at 2 = m/s 2 (.46 s) 2 = 4.5 m/s 2 39

40 from last page What distance did it fall? What's known? t = 0.46 s 1 = 0 2 =? ( 4.5 m/s) a = 9.8 m/s 2 d? equation??? 40

41 from last page _ = d t /t t What distance did it fall? _ d = t _ d = (.46s) _ = ( )/2 _ = [0 +( 4.5 m/s)]/2 _ = 2.3 m/s _ d = t d = 2.3 m/s (.46s) = 1.1 m 41

42 a d 2 = 1.5 m d a t 2 = 0.55 s This time a little girl drops a rock from rest from a height of 1.5 m. a) What elocity does it hit the ground at? b) What acceleration did it experience? a) b) 1 = 0 2 =? a =? 42

43 d 2 = 1.5 m t 2 = 0.55 s 1 = 0 2 =? a =? = d t = a = t = Δd t /t = 1.5 m/.55 s = 2.7 m/s _ 1 + = 2 2 = = 2( 2.7 m/s) 0 2 = 5.4 m/s a = Δ/t = 2 1 /t a = 5.4 m/s 0/.55 s a = 9.8 m/s 2 43

44 _ = _ = Δd t /t a = Δ/t 2 = 2 1 Δd t = t 44

45 A ball is dropped from a cliff and it takes 3.0 s to hit the ground. What elocity does it hit at?. a 1 = 0 t = 3.0 s d a 2 =? 45

46 ector directions graity is down so you list the alue as " " 46

47 1 = 16 m/s 2 = 0 t =?. Bad Billy throws a rock upward at 16 m/s. How long does it take to get to the top of it path? a d a 47

48 ball thrown upward at 16 m/s 48

49 This time bad Billy throws the rock downward at 15 m/s (from a new cliff) and it takes 3.0 s to hit the ground. a) What elocity does it hit the ground at? b) How high was the cliff? 1 = 15 m/s a a = 9.8 m/s 2 t = 3.0 s 2 =? d y =? d a 49

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53 You pull back a bow 37 cm and let it go. The arrow reaches a speed of 120 m/s as it leaes the bow wow! How long did it take? 53

54 You pull back a bow 37 cm and let it go. The arrow reaches a speed of 120 m/s as it leaes the bow wow! How long did it take? Δd t = t t = Δd/ t =.37 m/60 m/s t =.0062 s d p =.37 m 1p = 0 2p = 120 m/s t =? TM?... accel, 54

55 You pull back a bow 37 cm and let it go. The arrow reaches a speed of 120 m/s wow! How long did it take? How far does it go in 0.55 s? 55

56 You pull back a bow 37 cm and let it go. The arrow reaches a speed of 120 m/s wow! How long did it take? How far does it go (after it leaes the bow) in 0.55 s? d =? 56

57 You pull back a bow 37 cm and let it go. The arrow reaches a speed of 120 m/s wow! How long did it take? How far does it go in 0.55 s? The arrow stops in 4.0 cm? 57

58 duck in air: 1 = 345 ft/s 2 = 0 t =? d a =? 58

59 2 =? t = 3.06 s 1200 ft 59

60 1200 ft 1 = 345 ft/s 105 m/s d = 1200 ft 366 m g = 9.81 m/s 2 2 =? t = 3.06 s 60

61 1 = 345 ft/s 105 m/s d = 1200 ft 366 m g = 9.81 m/s 2 2 =? 1200 ft a = /t 2 = 1 + at 2 = ( 105 m/s) + [( 9.81 m/s 2 )3.06 s] 2 = 135 m/s 61

62 duck 62

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