University of California, San Diego
Physics 11 - Survey of Physics
||Physics 11 - Lab Exercise #1
Laboratory Exercise #1
Velocity and Acceleration
In this lab exercise you will attempt to bomb a toy train from the
balcony on the west side of WLH. Below is a drawing of the Laboratory
Apparatus. Your bombs --- small sandbags --- will be provided
As shown, you will take up ambush where
along the West balcony of the Warren Lecture Halls Building. You are to
drop your bombs blind. (As in bombing in bad weather or at night.)
Because you know you are to bomb blind, your
agents have placed Photogates A and B along the railroad track directly
below the two plumblines at points A and B. Whenever the train passes
through one of these gates you will hear a beep. Your agent has
also laid measuring tape along the balcony
between A and B, so you can measure whatever distances you may wish to
know. The only other piece of
equipment you will be issued is a stop watch. Again, it will be
up to you to use it the way you see fit. (Hint: Chewing on it won't help.)
Intelligence has given you the drop altitude h = 4.95m, and you are
guaranteed that the unsuspecting train will keep a constant speed along
the track between A and B, running parallel to the balcony.
Homework (10 pts)
You are to hand in your homework to your TA at the beginning of the
lab. Keep a duplicate for your own use. The homework consists of your detailed
strategy for hitting the train and should include:
Because you don't know the numerical values of certain parameters before
actually taking up battle station along the balcony, you will have to assign
them letter symbols in your battle plan. Extra credit will be given those
plans whose equations keep to symbols to the last minute, even for known
quantities such as g or h, before moving on to numerical
answers. Only symbols, not numerical values frozen and conglomerated, allow
you to predict what will happen should a certain quantity vary, e.g.
what do I have to do differently should I have to bomb on the moon, where
gravity is no longer the same?
Your written solution to nthe last problem on Homework #3 (The one about
Prof. Smith & the egg) -
use this as a guide for your lab strategy.
Include your solution in your homework submitted.
A brief description of the measurements that you will need to make.
An estimate of the accuracy with which your measurements need to be made.
A description of how you will determine when to drop your projectile.
Lab Report (40 pts)
You will, of course, perform the experiment with your lab partners,
and you may jointly calculate the results, but the report should be
your work alone, in your own words. Lab reports that are overly
similar will be penalized and may receive no credit. Reports are due
in lecture 1 week following the date of the experiment.
Your write-up of the lab should describe the reasoning behind your
strategy, the procedures you employed and your "score" of hits. Demonstrate
that your hits and misses are not random events. You must defend your
campaign quantitatively. Among effects you might consider are:
The completeness of your analysis will count more toward your Lab Score
than your record of hits and misses.
Air drag, air buoyancy
Velocity of the egg at release
Size (length, height, width) and speed of target.
The following rules apply:
Have fun, good bombing.
Students enrolled in Physics 11 only please!
Each member of your team must drop an bomb from a different position along
the balcony. Space yourself at least half a meter from your neighboring
bombers so hits and misses can be assigned unequivocally.
For each drop post one member of your team downstairs, as observer to keep
tab of hits versus misses, under TA supervision. Also to let you know if
you have missed the train sideways, presumably because you have pushed
the bomb a little too far over the ledge. It is a good idea to lay your
bomb ready on the edge of the balcony, and to give it a slight push when
it is time. Single shots only please.
The staging area for the train is separated from the walkway by plants.
These plants are for everyone to enjoy. Anyone caught stepping on or over
them, instead of using the access provided, will be penalized on his/her
Anyone caught leaning over the balcony, will be penalized
in his/her lab grade.
Highest scorers with correct computations may be invited, in a grand finale
contest at quarter';s end, to repeat the experiment with Prof. Gene Smith
taking the place of the train. Drops only, no throws. (But remember who
does the final grades.)
Physics 11 Labs
Ph 11 Home
modified: Tu., 12 Oct. 2004