Upcoming Deadlines Fifth Homework (Video analysis of jump) Due Thursday, Sept. 29 th (This week) Sixth Homework (Stop-motion Animation) Due Thursday, October 6 th (Next week) 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
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Upcoming Deadlines Fifth Homework (Video analysis of jump) Due Thursday, Sept. 29 th (This week) Sixth Homework (Stop-motion Animation) Due Thursday, October.
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Sixth Homework (Stop-motion Animation)Due Thursday, October 6th (Next week)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
Homework Assignment #6
In this assignment you will create a stop-motion animation of a falling object.
It can be a simple as a ball bounce cycle or (preferably) something more interesting, like a flour sack or a water balloon.
Because you will have to pose your object at different heights, you'll either need to suspend it from a string or have the motion occur on the ground with the camera positioned directly overhead.
Homework Assignment #6
If you have a webcam, an easy way to film a stop-motion animation is to use SAM Animation (http://www.samanimation.com/).
It's free software that runs on both Macs and PCs; it was developed at Tufts University as part of a National Science Foundation project for teaching using animation.
The software is designed so that it can be used by even elementary school children so you shouldn't have much trouble figuring it out.
Homework Assignment #6
Homework Assignment #6While I encourage you to help each other
out, for this assignment each person needs to create their own animation.
Finally, describe in a brief paragraph how you created your animation. Post your animation clip to your blog in an entry entitled "Stop Motion Animation of Falling.“
Due by 8am on Thursday, Oct. 6th 20 points (if late, 10 points)The top three animation clips in the class
will receive a bonus of 20 extra points.
Survey Question
You have some experience with creating stop-motion animation.
True or False?
The League of Extraordinary Gentlemen (2003)
In this scene, Sean Connery jumps out the side of a speeding car and lands on his feet.
A) Roll forward from where he lands, in the direction of the moving car.
B) Roll backwards from where he lands.
C) Land just as he does in the movie; this was actually done by a stuntman.
The League of Extraordinary Gentlemen (2003)In this scene, Sean Connery jumps out the side of a speeding car and lands on his feet. In reality, he would:
A) Roll forwardYou are moving at the same speed as the car when you jump out so you will roll forward.
Jumping out of a Car
Your path
You’ll start losing speed after you hit the ground so, relative to the car, you’ll fall behind as the car continues speeding along.
car
Creating ActionPart II
Estimating Terminal SpeedAir Resistance
Gravity
Terminal speed of a rectangular object (with the density of water) falling flat is approximately:
(Speed) = (50 m.p.h.) x T
where T is thickness in inches.
Thickness, T T Terminal Speed1/100 inch 1/10 5 m.p.h.
¼ inch ½ 25 m.p.h.
1 inch 1 50 m.p.h
4 inch 2 100 m.p.h.
9 inch 3 150 m.p.h
T
Terminal Speed & Density
The denser the material, the higher the terminal speed.The table gives the terminal speed for density of water.The terminal speed for wood is about the same as for water since the density of wood is close to that of water.The terminal speed for rocks is about 50%-75% larger since rocks are 2-3 times denser than water. Metals, like iron and copper, are 8-9 times denser than water so the terminal speed is about three times larger.
For example, a brick’s terminal speed is about 100 m.p.h.(Falling flat so thickness is 2 inches)
Drop the BallA golf ball and a ping pong ball are about the same size; golf ball is heavier. Drop both from the roof of a 10 story building. What happens?A) Balls hit the ground at the same time
and hit the ground with the same speed.
B) Balls hit the ground at the same time but the golf ball has a higher speed.
C) The golf ball hits the ground first but they both hit the ground with the same speed.
D)Golf ball hits the ground first and it also has a higher speed.
Drop the BallGolfBall
PingpongBall
D) Golf ball hits the ground first and it also has a higher speed.
Ping pong ball is less dense so its terminal speed is slower than the golf ball.
The golf ball falls faster, which also means it reaches the ground first.
Leaf/Paper Terminal Speed
The terminal speed of a leaf or sheet of paper is about 5 feet per second, which isabout 3½ miles per hour (or 2-3 inches per frame).
Terminal speed is reached after falling about 4 frames (flat orientation).
Air Resistance
Gravity
Density of paper about the same as wood.
Falling Coffee Filter
Tracked falling of a coffee filter.
Dis
tan
ce F
alle
n
Time
Accelerates in first 1/3 second
ConstantSpeed
Click
Air Resistance Threshold
Distance fallen from apex
Speed(miles per hour)
1 foot 5
4 feet 10
9 feet 15
16 feet 20
25 feet 25
49 feet 35
100 feet 50
400 feet 100
900 feet 150
Air resistance is only noticeable once an object’s speed gets close to its terminal speed.
This table gives the speed of an object from the distance it’s fallen it there is no air resistance.
For example, since a brick’s terminal velocity is 100 m.p.h. then air resistance is not noticeable for a 100 foot drop.