Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week)...

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Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion Animation) Due Wednesday, March 3 rd (In two weeks) 20 points (if late, 10 points) Bonus prize of 20 extra points to top three. For full schedule, visit course website: ArtPhysics123.pbworks.com Pick up a clicker, find the right channel, and enter Student ID

Transcript of Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week)...

Page 1: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Upcoming Deadlines

Fifth Homework (Video Analysis of a Jump)Due Wednesday, Feb. 24th (Next week)15 points (10 points if late)

Sixth Homework (Stop-motion Animation)Due Wednesday, March 3rd (In two weeks)20 points (if late, 10 points)Bonus prize of 20 extra points to top three.

For full schedule, visit course website:ArtPhysics123.pbworks.com

Pick up a clicker, find the right channel, and enter Student ID

Page 2: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Activating your Clicker

* Turn on your clicker.* Enter the channel number or letter for

joining this class. Hit Enter/Send key.* Clicker should read AP123S258* Type in your student ID; hit Enter/Send.Clicker is now ready to use; leave it on.

Hit any key to wake the clicker from sleep mode.

Page 3: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Extra Credit Opportunity

Go to any event at Cinequest Film Festival in downtown San Jose.

Turn in proof of attendance (receipt, photos, etc.) for 5 points of extra credit.

Page 4: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Extra Credit Opportunity

Student registration is $75 (ouch)

Turn in your receipt for 10 points of extra credit.

For info: www.gdconf.com

Attend the Game Developer’s Conference in San Francisco, on Saturday, March 13th

Page 5: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5In this assignment you’ll again use Tracker

software to analyze the motion of a moving object from video reference.

First, shoot some reference of yourself doing a running jump.

Position your camera so that you're in frame the entire time that you're in the air.

Stage the jump to be in profile. Shoot at least 5 takes, even if they are more or

less the same.

Page 6: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5

Original Video Reference

Page 7: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5Import your video reference into the Tracker

software (as in previous homework).Track the center of your waistline or beltline,

which is approximately the location of your center of gravity.

Marking your position from the time you leave the ground until you’ve landed.

After tracking your motion, upload the screen image from Tracker to your blog into a post called "Video analysis of path of action".

Page 8: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5

ParabolicPath of Action

Straight Line

Parabolic Curve

Page 9: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5

Finally, rewind your video to the first frame of your jump and from the "File" menu select "Record -> Quicktime Movie".

Hit the play button and allow the clip to play until the end of your jump. Next, in the "Capturing Quicktime MOV" window click "Save As" to save the recording.

Page 10: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5

Video Reference with Tracking

Page 11: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Homework Assignment #5

Check that your saved Quicktime movie has the track showing the path of action then put both clips (original and with tracking) in your blog post using YouTube or Vimeo.

This assignment is due by 8am on Wednesday, Feb. 24th (week from today).

15 points (10 points if late)

Page 12: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Survey Question

So far the pace of the class has been:

A)Too fastB)A little fastC)About rightD)A little slowE)Too slow

Page 13: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Review QuestionThe motion graph for a ball drop, going from the apex until the ball just touches the ground, looks like:

A) B) C) D)

Page 14: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Motion Graph of a Ball Drop

Frames

Heig

ht

D)

Page 15: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Arcs in Animation

Page 16: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

Page 17: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

We have already discussed several of these principles of animation, specifically:

Page 18: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

Today we will discuss arcs and how they relate to animated motion.

Page 19: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Arcs of Motion

Motion usually follows an arc, which may be simple, like a circle, or very complex and irregular.

Page 20: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Importance of Arcs

One of the major problems for the inbetweeners is that it is much more difficult to make a drawing on an arc.Drawings made as straight inbetweens completely kill the essence of the action.

Disney animation legends Frank Thomas and Olie Johnston write:

Wrong

Right

Page 21: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Circular Arcs

Circular arcs are common since motion is often around a fixed pivot point, such as a joint.

Page 22: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Speed in Circular Motion

Rotational Speed: Revolutions per secondTangential Speed: Total distance per

secondSame Rotational Speed

Different Tangential Speeds

Page 23: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Throwing ArmTangential

Speed

The longer the throwing arm, the greater the tangential speed so the farther it can throw. Sling lengthens

the arm at almost no cost in the weight.

Doubling the speedquadruples the range!

x2

Page 24: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Timing on Circular Arcs

In this golf swing the motion:• Slows out (accelerates) to hit the ball• Uniform after the hit• Slows in as the swing finishes follow-through

A circular arc is a simple path of action but the timing may be complex and textured.

Slow out

Unifor

m

Slow in

Page 25: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Non-Uniform Circular MotionTwo common types of motion on circular arcs that have non-uniform timing and spacing are:

Exponential Spacing Pendulum Spacing

Example:Tipping over

Example:Stride inwalking

Page 26: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Tipping Over

Tipping over is a common example of motion on a circular arc. Two ways to tip over:

XX

Center tipped past point of contact

Center past an edge

Page 27: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Tipping Rotation

A brick rotates about a point as it tips;that point is the center of a circular arc.

XX

Friction tends to keep the brick from sliding until it loses contact with the table.

X

X

Page 28: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

As the slope of the incline increases, the acceleration itself accelerates.

Exponential Spacing1

3

7

1

2

3

4

Constant acceleration (Odd Rule)Release

5

1

2

3

4

Release

Exponential Spacing

Page 29: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Slowing out from a tipping point is very slow initially, but then accelerates rapidly.

Rolling off a Tipping Point

1 2 3 4 56

7

8

Peak

Page 30: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Video Reference of Tipping Brick

http://www.youtube.com/watch?v=otYAYMZ4iGg

Page 31: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Anticipation & Exponential Spacing

Texture of the timing as the brick tips over creates anticipation, which you want at the start of a scene

Also notice motion blur near

top of brick, which has large

tangential speed.

Page 32: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Pendulum SpacingA pendulum’s path of action is also a circular arc but the spacing is very different from the exponential spacing of tipping over.

Page 33: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Spacing & Timing in Swinging

A pendulum will slow in and out as it swings back and forth, the same as a ball rolling in a half-pipe.

Most of the texture in the timing is at the endpoints; the timing is even in the center.

Page 34: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Pencil Test Example

http://www.youtube.com/watch?v=xuoJdNGxffU

Page 35: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Motion Graph for PendulumThe motion graph (angle vs. frame) shows that the timing is mostly textured (curves the most) at the apexes.

Frame

An

gle#1

#4

#7

FASTFAST

SLO

W

SLOW

SLOW,again

SLO

W,

agai

n

Ball goes fastest around the bottom but the speed is almost constant.

Page 36: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Uniform Rotation in PerspectiveThe timing for uniform rotation has texture when seen in perspective.

Half orbit

Quarterorbit

Rotation from key #1 to #5 in background takes twice as long as from #6 to #8 in foreground.

Page 37: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Swinging in Perspective

Visually the timing has even more texture when the swing occurs in perspective.

Page 38: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Who Framed Roger Rabbit? (1988)

The opening sequence in Who Framed Roger Rabbit? makes great use of the textured timing of arcs in perspective.

Animation byRichard Williams

Page 39: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Who Framed Roger Rabbit? (1988)

http://www.youtube.com/watch?v=sLNqtU-gYPc

Page 40: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Demo: Don’t FlinchPendulum swings back and forth yet it doesn’t hit your face.

Page 41: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Bowling Ball Pendulum

This video clip lets you experience what it’s like to do this demo.

Click

http://www.youtube.com/watch?v=UNsD15GjWWE

Page 42: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

SpiralsA spiral is just a circular arc with a radius that’s either increasing (spiral out) or decreasing (spiral in).

Concept art fromPirates of the Caribbean 3

Page 43: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Rotational Speed in SpiralsIf the radius decreases without pulling the object inward then the rotational speed increases (due to shrinking radius) but the tangential speed stays constant.

Spiral In

Spacings along the curve stay constant.

Page 44: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Demo: Interrupted Pendulum

Tangential speed does not increase due to the pendulum whipping around the interrupt bar.

Energy is not increased by the interrupt bar so ball swings back to the same spot.

Bar

An “interrupt” bar changes the radius of the arc for a pendulum.

Page 45: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Rotation in Spirals (cont.)If the radius decreases by pulling the object inward then the rotational speed increases due to shrinking radius and due to an increase in the tangential speed.

Spiral In

Spacings along the curve get

bigger and bigger.

Page 46: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Demo: Skater’s Spin

SlowRotation

FASTRotation

Exert a force to pull hand weights toward my body, causing a big increase in rotational and tangential speeds

Page 47: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Rotation in Spirals (cont.)If the tangential speed decreases (say by friction) but inward force constant then the rotational speed still increases.

Spiral In

Spacings along the curve get

shorteryet it

stillspinsfaster

and faster.Coin Vortex

Page 48: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Rotation in a Spirals

In summary, typically as an object rotates in a spiral, the rotation speed increases as the radius decreases.

So as radius goes down,

the r.p.m.s go up.

However the spacings may get longer, or shorter, or stay constant!

Page 49: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

How Does the Brick Fall?

Does the brick rotate and then fall down the side of the table?

XX

No! The brick does not fall this way.

XX

4

3

2

1

Page 50: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Video Reference of Tipping Brick

http://www.youtube.com/watch?v=otYAYMZ4iGg

Page 51: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Forces on the Tipping Brick

XX

The table pushes on the brick upward and towards the right.

Gravity pulls downward

Center of the brick shifts down and towards the right.

If no table…

Page 52: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Pushing Off by the TableThe table pushes away on the brick, which causes the brick to move away from the table as it falls.

X

X

X

Once it loses contact with the table, only the force of gravity accelerates the brick.

Page 53: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Centrifugal Force

What we see

What theinsect feels

Insect inside a can rotating in a circle

When we move on an arc, it seems to us as if there is an outward force, pushing us away from the center of the circle.

Physicists call this apparent force the centrifugal force.

Page 54: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Class Demo: Bucket Overhead

I will put a bucket full of water over my head without getting wet. How?

CentrifugalForce

By rotating it fast enough.The water stays in the

bucked as if pressed into it by a centrifugal force.

You experience centrifugal force on taking a sharp turn

Page 55: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Wile E. Coyote & Loop-D-Loop

Watch carefully as Wile E. Coyote travels in a circle around a natural arch bridge.

http://www.youtube.com/watch?v=p4YxdXw9evc

From “Beep Beep” (1952)

Page 56: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Wile E. Coyote & Loop-D-Loop

In reality, it is impossible to travel upside-down, as Wile E. Coyote does in this scene. True or False?

“Beep Beep” (1952)

Page 57: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Wile E. Coyote & Loop-D-Loop

False.If his speed is high enough then he stays in contact with the arch, just like the water in the spinning bucket.

Page 58: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Demo: Loop-the-Loop

If the speed of the ball is large then not only does it stay on the track, the ball even pushes outward and against the rail.

Velocity

Release

Page 59: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

GAP

Demo: Loop-the-Loop

Ball could even circle a loop with a gap, if the speed was just right so gravity was equal to the centrifugal force.

Velocity

Release

Page 60: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Simulated Gravity

Centrifugal force could be used to simulate gravity in a space station.

With the appropriate rotational speed a person on the outer rim would feel as if they stood on the surface of Earth.

Scientifically accurate in the movie 2001: A Space Odyssey (1968)

Rotation

Page 61: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

2001: A Space Odyssey (1968)

Page 62: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Simple Spinning1

5

7

3

1Arbitrary 2

3

4

In simple spinning, the angle rotates at a constant rate.

A brick tipped 45º as it loses contact with the table will fall spinning about 30º every two frames.

A falling brick may turn by simple spinning around its center.

Page 63: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Tumbling1

5

7

3

1Arbitrary 2

3

4

There is no simple way to describe tumbling. However, the brick’s center still follows the same parabolic path of action.

A falling brick may also turn by a more complicated tumbling motion.

Page 64: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Tennis Racket Theorem

When an object turns about its long or its short axis, it tends to spin.

When an object turns about its middle axis, it may tumble.

SPIN

SPIN

Page 65: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Irregular Objects

SPIN

SPIN

SPIN

SPIN

Page 66: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Spin or Tumble?

Rotation around two of these axes is spinning.The axis of rotation that tumbles is:A)Head-to-toe axisB)Side-to-side axisC)Front-to-back axis

A

B

C

Page 67: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Spin or Tumble?

B) Side-to-side axisB

Rotating along this axis typically results in irregular tumbling.

Spinning is possible but requires more control than along the other two axes.

Page 68: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Rolling & Slipping

1 2 3 4 5 6 7

Rolling ball turns one revolution when it travels a distance equal to three times its diameter (actually 3.1416 diameter)

ROLLING

1 2 3 4 5

SLIPPING

Slipping and rolling are both uniform in spacing and rotation.

Page 69: Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24 th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion.

Next LectureCreating Action

By Wednesday of next week:Complete the 5th homework

(Video analysis of Path of Action)

Please return the clickers!