Crayon Physics worksheet
Team name:No Flux Given
Team member 1: Drew Curto
Team member 2: Sydney Hauver
Team member 3: Audrey Sheetze
Edit this document, inserting answers to the questions where requested in red. Upload to
our Moodle site before the end of class.
As you answer these questions, keep in mind that since I don’t know how you are
arriving at an answer, you must document your method so that I understand exactly how
you did it and where your numbers come from. This probably means a screencap, a
couple of sentences of explanation with (probably) an accompanying equation, and a
number with units.
1. g
What is the gravitational acceleration in Crayon Physics?
g = __12.37___ ± ____.58__ gridlines/s2
Describe (in a couple of sentences) how you measured g and the error on g. This
may involve a screencap if it helps you make your point.
We dropped an object of mass 1 from a height of 26 gridlines with an initial velocity
of 0. Then we dropped it 4 times and got an average of 2.05 seconds to hit the
ground. Using the formula of D=vit + at^2/2. Solved for a knowing the only force
acting on it was gravity and thus the acceleration must only come from the
acceleration due to gravity. The only thing that we measured was time as mass was
given to us(mass is measured in boxes) and distance is measured in gridlines, so
because our stopwatch measured in milliseconds so our error on t was .05, so we
found the error by doing problem with time having that error added and then
subtracting from it the equation without error on time. (So d=vit+a(t+error)^2/2d=vit+a(t)^2/2).
2. Coefficient of restitution?
Fill in this table for the regular (default) ball, for a drawn object, and for an extra ball
(dragged from the bottom of the level editor). You can omit errors on this
measurement.
Default ball
Generic object
Extra ball
Physics 181 labs
vinitial
(gridlines/s)
17.93
17.93
17.93
vfinal
(gridlines/s)
2.49
2.49
4.97
Coefficient of
restitution
.139
.139
.277
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Crayon Physics worksheet
How did you measure these values?
We found the area if each circle to get the ball’s mass, and made a generic object of
mass 1. Then because we knew the “gravity”, height, mass, and initial velocity of 0,
we were able to find the velocity before it hit the ground through conservation of
energy. Then we put a pin where the object reached it’s max height from it’s bounce
off the ground. Using that as the final height and knowing it would have no velocity
at the top of the arc we found the velocity of the bounce. Then we solved for COR by
doing absolute value of v1(Velocity of ball when it hits the ground) divided by
v2(velocity of ball as it bounces)
3. Is Crayon physics 3D or 2D?
Is Crayon physics (A) two-dimensional, or (B) a 2D slice of a 3D world?
Answer, explanation and measurement (with errors) that proves which of (A) or (B)
is true. Probably a screencap of your level.
4. Conservation of momentum (Challenge / extra credit)
Can you arrange a scenario that quantitatively tests whether Crayon Physics
respects conservation of momentum (either linear or angular)? This is not a
rhetorical question: I’m pretty sure that momentum is conserved, but I haven’t been
able to figure out a way to measure it cleanly.
Physics 181 labs
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Crayon Physics worksheet
Please do a generic collision (not the special case of zero net momentum), since
that’s a better probe of the physics engine. Note that momentum is not conserved if
you click on the ball using the “force arrow” tool: this applies a lone external force (a
force that is not part of an action/reaction pair), violating Newton’s third law and
invalidating conservation of momentum.
Physics 181 labs
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