PHYSICS 113 – Recitation Assignment 8
Name
Recitation Assignment # 8
November 15, 2006
You may complete this in class. However, if you are unable to do so, it is expected that you
complete this for recitation next time.
If you have any questions, please ask.
Note that it is expected that you will look at your previous recitation assignments (and the online
documentation!) to help you understand the assignment. Please refer to these frequently, and try
to understand what the code is actually doing.
New Python Concepts: controls (sliders and buttons), lablels, functions,
New Physics Concepts: Friction
1. I have put a file called prog8 starter.py on the course homepage. Please download it into
your recitation directory.
2. There is a note in the incomplete program where you should add the physics. In particular, I
want you to add a loop which will shoot a projectile with an initial velocity given by ball.v,
until the ball has a y-position lower than zero. In particular, I also want you to have an
acceleration of: −gm/s2ˆ
jdue to gravity (where g=9.8 is pre-set into the program, and can
be adjusted). In addition, you want to introduce an air resistence of:
Fr=1
2CρAv2
where Cis a geometric factor (typically between 0.3 and 1, and, ρis the density of the
air, ∼1.3kg/m3, and Ais the surface area of your object (say 0.01m2for something like a
baseball). In this case, we have a coefficient of:
Fr'0.003kg
mv2
or a friction deceleration of
ar'0.003(meters)−1v2
in the opposite direction of the direction of motion.
Note that in this approximation, the mass of the ball never enters into it at all!
Add in the air resistence term as well. The “mu” in your code should be a normalizing factor
such that:
ar'µ×0.003(meters)−1v2
3. That’s it! That’s all that’s required. However, if you’d like to have some fun, you may try
some of the following:
