I would suggest you take notes like this: You will need 4 page sides (2 pages, front & back) Leave page 1 blank and start on page #2. (See next slide) I would suggest you take notes like this: VELOCITY EQUATIONS (1) I would suggest you take notes like this: Starting from rest vi = 0 (2) Already moving vi ≠ 0 (3) 7 5 4 3 1 2 Velocity (m/s) 6 vf 0 vi 0 1 2 3 4 5 6 7 Time (s) Page 2 8 9 10 11 12 13 7 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 How would we calculate Vavg? 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 vavg = (vi + vf)/2 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 What about acceleration? 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 a = Δv/Δt 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 a = Δv/Δt 6 4 5 This is just the 'rise' divided by the 'run'. So the slope of velocity time graph gives us acceleration! 1 2 3 vavg vi 0 Velocity (m/s) } vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 a = Δv/Δt a = (vf ­ vi)/t 5 4 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 a = Δv/Δt a = (vf ­ vi)/t 5 4 IF: vi = 3 vavg 1 2 Then: a = vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 a = Δv/Δt a = (vf ­ vi)/t 5 4 IF: m vi = 0 /s 3 vavg 1 2 Then: a = vf/t vf = at vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 If vi < or vi > 0: 3 4 5 (Which do we have here?) 2 Velocity (m/s) 6 7 vf 0 1 vi 0 1 2 3 4 5 6 7 8 9 10 11 Time (s) (Page 3) NEW GRAPH!!!! 12 13 7 vf If vi < or vi > 0: 5 EXACTLY the same as our other graph!!! 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 vavg = (vi + vf)/2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 If vi < or vi > 0: a = Δv/Δt 5 a = (vf ­ vi)/t 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 If vi < or vi > 0: a = Δv/Δt 5 a = (vf ­ vi)/t 4 vavg 2 3 at = vf ­ vi 1 vi vf = vi + at 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 Page 1 How to 'READ' the equations: vf = vi + at How fast I'm going now depends on: Was I moving to start out? AND Did I speed up or slow down, and if so, for how long? How would we calculate the area of this triangle? 7 How would we calculate the area of this triangle? 5 4 3 vavg 1 2 Velocity (m/s) 6 vf 0 vi 0 1 2 3 4 5 6 7 Time (s) Page 2 8 9 10 11 12 13 7 How would we calculate the area of this triangle? 4 5 Area=½ b*h 1 2 3 vavg vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 How would we calculate the area of this triangle? 5 Area=½ b*h 4 But instead we have: 3 vavg 1 2 Area=½ v*t vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 How would we calculate the area of this triangle? 5 Area=½ b*h 4 But instead we have: 3 vavg 2 Area=½ v*t 1 click here DISPLACEMENT vi 0 Velocity (m/s) 6 vf 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (s) WHAT DOES AREA TELL YOU IN THIS CASE? (HINT: Think Units, Think STD Lab) 13 Page 1 Interpreting Graphs: The slope of a Displacement vs. Time graph tells us ___________. The slope of a Velocity vs. Time graph tells us ________________. The area under a Velocity vs. Time graph tells us ______________. Interpreting Graphs: The slope of a Displacement vs. Time graph tells us ___________. Velocity The slope of a Velocity vs. Time graph tells us ________________. Acceleration The area under a Velocity vs. Time graph tells us ______________. Displacement 5 4 3 vavg 1 2 Velocity (m/s) 6 7 Remember from before: vf For vi=0: a=vf/t vf=at 0 vi 0 1 2 3 4 5 6 7 Time (s) Page 2 8 9 10 11 12 13 5 4 Displacement = ½ v*t 1 2 3 vavg vi 0 Velocity (m/s) 6 7 Remember from before: vf For vi=0: a=vf/t vf=at 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 4 Displacement = ½ v*t 3 vavg 1 2 d = ½ (at)*t vi 0 Velocity (m/s) 6 7 Remember from before: vf For vi=0: a=vf/t vf=at 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 4 Displacement = ½ v*t 3 vavg 2 d = ½ (at)*t 1 d = ½ at2 vi 0 Velocity (m/s) 6 7 Remember from before: vf For vi=0: a=vf/t vf=at 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 4 Displacement = ½ v*t 3 vavg 2 d = ½ (at)*t 1 d = ½ at2 vi 0 Velocity (m/s) 6 7 Remember from before: vf For vi=0: a=vf/t vf=at 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (s) What does the 'slope' tell us again? 13 d = area under graph 5 3 4 vavg 2 Velocity (m/s) 6 7 vf 0 1 vi 0 1 2 3 4 5 6 7 Time (s) Page 3 8 9 10 11 12 13 d = area under graph 5 top triangle: 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 d = area under graph 5 top triangle: d= ½ at2 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 d = area under graph 5 top triangle: d= ½ at2 bottom rectangle: 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 d = area under graph 5 top triangle: d= ½ at2 bottom rectangle: d= vi * t 2 3 4 vavg 1 vi 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 d = area under graph 5 top triangle: d= ½ at2 bottom rectangle: d= vi * t 3 4 vavg 2 Total area: 1 vi d= vit + ½at2 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 d = area under graph 5 top triangle: d= ½ at2 bottom rectangle: d= vi * t 3 4 vavg 2 Total area: 1 vi d= vit + ½at2 0 Velocity (m/s) 6 7 vf 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Time (s) ... and what does the 'slope' tell us again? Page 1 How to 'READ' the equations (cont.): d = vit + ½at 2 Where I'm at now depends on: Was I moving to start out with, and if so, how much time has passed since then? AND Did I speed up or slow down during this time? Your notes should now look like this: VELOCITY EQUATIONS How to 'READ' the equations: vf = vi + at How fast I'm going now depends on: Was I moving to start out? AND Did I speed up or slow down, and if so, for how long? d = vit + ½at2 Where I'm at now depends on: Was I moving to start out with, and if so, how much time has passed since then? AND Did I speed up or slow down during this time? Interpreting Graphs: Velocity The slope of a Displacement vs. Time graph tells us _________. Acceleration The slope of a Velocity vs. Time graph tells us ______________. The area under a Velocity vs. Time graph tells us ___________. Displacement (1) Ah...beautiful, colorful, candy­like notes: Starting from rest vi = 0 Already moving vi ≠ 0 vavg Displacement Displacement vavg = (vi + vf)/2 a = Δv/Δt a = (vf ­ vi)/t IF: vi = 0 m/s d = ½ at2 vavg = (vi + vf)/2 If vi < or vi > 0: a = Δv/Δt a = (vf ­ vi)/t at = vf ­ vi Then: a = vf/t vf = at d = area under graph top triangle: d= ½ at2 bottom rectangle: d= vi * t vf = vi + at Total area: d= vit + ½at2 (2) (3) HOW FAR EXAMPLE: PAGE 4: (4) 5 4 1 2 3 How far does this graph get us? 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 4 3 2 1 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 1 2 3 4 vf vi 0 Velocity (m/s) 6 7 vit ½at2 d= + 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 a = Δv/Δt vf 1 2 3 4 a = vf ­ vi tf ­ ti vi 0 Velocity (m/s) 6 7 vit ½at2 d= + 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 a = Δv/Δt vf 3 4 a = vf ­ vi tf ­ ti 2 a = (4 ­ 0)m/s (4 ­ 0)s 1 m 2 a = 1 /s vi 0 Velocity (m/s) 6 7 vit ½at2 d= + 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 vit ½at2 d= + 5 1 2 3 4 vf vi 0 Velocity (m/s) 6 a = 1 m/s2 0 1 2 3 2 4 5 d = ½at d= ½(1m/s2)(4s)2 d= 8m 6 7 Time (s) 8 9 10 11 12 13 5 2 3 4 vi 1 d = ½at2 d = 8m 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 2 3 4 vi 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 vf 5 2 3 4 vi 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 vf 5 4 vi 2 3 d= vit + ½at2 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 vf 6 7 d= vit + ½at2 5 vi 4 a = vf ­ vi tf ­ ti 2 3 d= vit + ½at2 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) a = Δv/Δt 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 vf 6 7 d= vit + ½at2 5 vi 4 a = vf ­ vi tf ­ ti 2 3 d= vit + ½at2 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m a = (6 ­ 4)m/s (12 ­ 8)s a = 0.5 m/s2 0 Velocity (m/s) a = Δv/Δt 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 7 d= vit + ½at2 m 5 vf 4 vi 2 3 d= vit + ½at2 d = 4m/s*4s+½(0.5m/s2)(4s)2 d = 20m 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) 6 a = 0.5 /s 2 0 1 2 3 4 5 6 7 Time (s) 8 9 10 11 12 13 5 4 2 3 d= vit + ½at2 d = 4m/s*4s+½(0.5m/s2)(4s)2 d = 20m 1 d = ½at2 d = 8m d = vi*t d=4m/s*4s d=16m 0 Velocity (m/s) 6 7 d= vit + ½at2 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (s) dtotal = 8m + 16m + 20m = 44m 13 HOW FAR EXAMPLE: d=16m d = 20m d= 8m PAGE 4: a = Δv/Δt a = vf ­ vi tf ­ ti d = vi*t d=4m/s*4s d=16m a = Δv/Δt a = vf ­ vi tf ­ ti a = (4 ­ 0)m/s (4 ­ 0)s a = (6 ­ 4)m/s (12 ­ 8)s a = 1 m/s2 a = 0.5 m/s2 d= vit + ½at2 d = 4m/s*4s+½(0.5m/s2)(4s)2 d = 20m d = ½at2 d= ½(1m/s2)(4s)2 d= 8m dtotal = 8m + 16m + 20m = 44m (4) Page 5 (Hey wait a minute, you said there were only 4 pages of notes?!?!) Formulas Variables Solved/Known d vavg = Δd/Δt vi vf * * * vavg = (vi + vf)/2 * * vf=vi+at * * * a * a = Δv/Δt d= vit + ½at2 vavg * t * * * * * * * * THIS CAN BE PRINTED OUT FROM THE PHYSICS WEBPAGE!!! I would suggest you take notes like this: If you are going to transfer the equation sheet into your notes, give them their own page. They're that IMPORTANT!!! (5)