Upcoming Deadlines

1. Upcoming Deadlines Pick up a clicker, find the right channel, and enter Student ID Homework #9 – Stop-motion character Animation Due Thursday, November 10th (Next Thursday) 20 points (10 points if late); 20 point bonus to top 3 For full schedule, visit course website: ArtPhysics123.pbworks.com

2. Homework Assignment #9 In this assignment you will create a simple stop-motion animation of a moving character. For your character, use a doll or stuffed animal that's easily posed. You may even use an inanimate object, such as a table lamp, as long as you can animate it so that it looks like a character.

3. Homework Assignment #9 http://www.youtube.com/watch?v=EiEVdTQGGTM

4. Homework Assignment #9 Your animation should be composed of at least a dozen different images but you can use the same photo in two or more frames to get timing right. Try to make the motion of the character as realistic as possible so that your audience will momentarily forget that it's not actually alive. In homework assignment #6 you created a stop-motion animation of an inanimate falling object; if you're not happy with how you produced your earlier animation then re-read that assignment for alternative ways of creating stop-motion.

5. Homework Assignment #9 You may work together with one or more classmates to create a single animation for the team. Clearly indicate the work done by each person, for example if different persons animate different characters or different scenes. More is expected from a team effort; an animation created by a three person team should present three times as much work as a solo effort.

6. Homework Assignment #9 Post your animation clip to your blog in an entry entitled "Stop-Motion Character Animation.“ Assignment due 8am on Thur., November 10th 20 points (if late, 10 points) The top three clips in the class, as selected by a celebrity judge, will receive a bonus of 20 extra points.

7. Extra Credit Opportunities • Attend the Star Party this Saturday. Telescope viewing, talks and hands-on activities on Tower Lawn and Science 142 • Attend the “Technology of Animation” event, featuring guest speaker Jeffery Katzenberg, at the computer history museum in Mountain View. Registration is at the bottom. http://www.computerhistory.org/events/#technology-animation • Attend any event at the San Francisco International Animation Festival (November 10-13). Present proof of your attendance to any of these (receipt, photos, etc.) for 10 points of extra credit.

8. Survey Question Writing the term paper was: • Rather enjoyable  • Somewhat enjoyable • OK • Somewhat painful • Rather painful 

9. Survey Question For Dr. Kaufman, do you think reading the term papers was: Rather enjoyable  Somewhat enjoyable OK Somewhat painful Rather painful 

10. Review Question • Stride • Squash • Passing Position • Stretch • Same weight at all times At which position do you exert the least weight on the ground? Stretch P.P. Stretch P.P. Stride Stride Stride Squash Squash

11. Force Plate Experiments Upward centrifugal force due to your motion lightens your weight. Stride C) Passing Position Can measure weight shift during walk cycle using force plates. Squash Squash Stretch Stretch Body Weight Passing Position Passing Position

12. Review Question Compared with the walking speed of a 6 foot man, the walking speed of a 150 foot giant is… • 25 times slower • 5 times slower • About the same • 5 time faster • 25 times faster • than the man. Jason and the Argonauts

13. Stride Time and Stride Length D) 5 times faster The giant is x25 taller so each giant stride is x25 longer (in distance). But the stride time for the giant is x5 more than the man’s stride. So the giant’s speed is x5 faster than the man. Distance Speed = ------------ Time

14. Jason and the Argonauts (1963) Notice how the timing of the giant’s walking gives the sense of his massive scale. Although the gait his lumbering, the giant easily catches the running men. http://www.youtube.com/watch?v=2BaLKYlC07w

15. WalksPart II

16. Ray Harryhausen Ray Harryhausen, the master of stop-motion animation, created the special effects in many films from the 1940’s to the 1970’s One of his best scenes in the skeleton battle in Jason and the Argonauts

17. Skeleton Battle Scene http://www.youtube.com/watch?v=0gKD7qy98-E Notice how the animated skeletons walk (conveniently, we see their pelvis and leg bones).

18. Energy and Walking So far we’ve examined walking from the point of view of forces. An alternative approach is toexamine theenergy expendedin walking. We’re inherently lazy so many actions that we perform unconsciously while walking reduce energy expenditure.

19. Home Demo: Silly Walks http://www.youtube.com/watch?v=IqhlQfXUk7w Try walking around as John Cleese, who is the Minister of Silly Walks. You will find that you use much more energy than normal walking.

20. Energy Budget (Inanimate) Moving objects have an energy budget. For inanimate objects, this budget is: Kinetic Energy (K) – Energy due to their speed Potential Energy (P) – Energy due to their height Friction Loss (F) – Energy lost due to friction forces K = 40 P = 40 F = 20 K = 0 P = 100 F = 0 K = 20 P = 70 F = 10 Total Energy = 100

21. Demo: Ball Races Marbles start at equal height and race on these rail tracks (almost no friction). Track B has a long dip in the center. Winner? A) Ball A; B) Ball B; C) Near perfect tie. Hint: Kinetic energy + Potential energy stays constant.

22. Demo: Ball Races B) Ball B is the winner. K = 50 P = 50 F = 0 K = 50 P = 50 F = 0 K = 50 P = 50 F = 0 K = 0 P = 100 F = 0 K = 50 P = 50 F = 0 K = 50 P = 50 F = 0 K = 100 P = 0 F = 0 Ball B has a high speed in the center section.

23. Energy and Wile E. Coyote http://www.youtube.com/watch?v=h2j_n0sRXeU From Going, Going, Gosh The energy budget here is wrong because the rock, after rolling down hill, flies back up to a point higher than from where it started!

24. Energy Budget, Bouncing Kinetic Energy Potential Energy Friction Losses K = 45 P = 5 F = 0 K = 36 P = 4 F = 10 K = 50 P = 0 F = 0 Total Energy = 50

25. Energy Budget, Sack Drop K = 0 P = 200 F = 0 Flour sack sitting on a shelf starts with potential energy. After it settles, all the energy is lost to friction forces. What is the kinetic energy when fallen half-way down? K = ??? P = 100 F = 5 (Air resistance) • Zero • 200 • 100 • 95 • 105 K = 0 P = 0 F = 200 Kinetic Energy Potential Energy Friction Losses

26. Energy Budget, Sack Drop K = 0 P = 200 F = 0 D) 95 The total budget (K+P+F) has to equal 200. If there was no air resistance then the falling speed would be greater and K=100. With more air resistance, the friction loss would be greater and kinetic energy less. K = 95 P = 100 F = 5 (Air resistance) K = 0 P = 0 F = 200 Kinetic Energy Potential Energy Friction Losses

27. Energy Budget (Animate) Animate objects can increase their energy budget by doing work. Work Input (W) – Energy added by doing work. Kinetic Energy Potential Energy Friction Losses Work Input K = 0 P = 0 F = 0 W = +0 K = 300 P = 0 F = 20 W = +320 K = 100 P = 0 F = 10 W = +110

28. Energy Budget in Jumping Slow down as you rise to apex so kinetic energy (K) goes down. K = 90 P = 200 F = 60W = +350 K = 120 P = 175 F = 55W = +350 K = 200 P = 100 F = 50W = +350 Leg muscles do work as you push off when jumping. K = 0 P = 50 F = 0W = 0 Most of the friction loss is during push but a little loss due to air resistance.

29. Energy Budget in Walking K = 100 P = 100 F = 0W = +0 K = 100 P = 100 F = 60W = +60 Walking takes work due to all the frictional losses.

30. Simplified Walking Model Pelvis is a double-forked bar with spherical hip joints. Legs are straight bars without knees, ankles, or feet. Center of gravity rises and falls as an inverted pendulum. CG Passing Position Stride CG Passing Position Stride Walking Forward Passing Position We have to do work to raise the CG and much of that energy (30-40%) is lost to friction.

31. Simplified Walking Model

32. Pelvic Rotation Without Rotation As the passing leg swings forward, the hips swing around, rotating about the planted leg. With Rotation

33. Pelvic Rotation

34. Pelvic Rotation & Center of Gravity Pelvic rotation keeps the center of gravity from dropping as far during the stride (keeping step length the same). CG Path of Action ofCG with Rotation Without Rotation Passing Position Stride CG Stride Passing Position Walking Forward Passing Position Walking is more efficient with pelvic rotation.

35. Pelvic List In the passing position the pelvis drops slightly on the non-weight bearing side. This motion is called “pelvic list.” Note that the knee has to bend to lift the foot, otherwise it would drag the ground.

36. Pelvic List

37. Pelvic List & Center of Gravity CG Path of Action ofCG without List Pelvic list keeps the center of gravity from rising as much when the body passes over the weight-bearing leg, keeping the center of gravity on a flatter path of action. With Pelvic List Passing Position Stride CG Passing Position Stride Walking Forward Passing Position Walking is more efficient with pelvic list.

38. Knee Flexion of Weighted Leg Knee flexes about 15 degrees immediately after heel strike and remains flexed until the center of gravity passes over the weight bearing leg. Walking Forward

39. Knee Flexion of Weighted Leg

40. Knee Flexion Path of Action of CG without Flexion CG Knee flexion keeps the center of gravity from rising as much during the passing position. Knee flexion also reduces the impact on the body at heel strike. With Flexion Passing Position Stride CG Passing Position Stride Walking Forward Passing Position Walking is more efficient with knee flexion.

41. Heel and Toe The heel and toes of the foot combine with knee flexion to reduce the rising and falling of the center of gravity. Flexion reduces the leg length Toes increase leg length Heel increases effective length of the leg

42. Energy in Four-legged Walks Four-legged walking gait alternates passing position and stride between fore and hind legs to minimize energy required to lift the center of gravity. x x x x x Center of Gravity Height The Journal of Experimental Biology 207, 3545-3558 (2004)

43. Next LectureLimbs and Joints Homework 9 Stop Motion Animation #2 Due Thursday, November 10 Please turn off and return the clickers!