Barbie Lab Report
Experimenters: Gama, Muraj, TK
Purpose: The purpose is to get Barbie as close to the ground as possible without touching the
ground, using rubber bands and string. Barbie must be dropped from the top of the bleachers.
The string cannot be longer than the rubber bands. There cannot be a practice fall with Barbie.
Hypothesis: Barbie will drop a total of 5.5 meters, leaving .9 meters between Barbie and the
ground.
Materials: Barbie doll, Uniform rubber bands, string, hanging masses
Safety: Exercise normal safety precautions in the laboratory
Procedure:
1. Find mass of Barbie and height of bleachers.
2. Calculate the spring constant of one rubber band. F=-kx
3. Since Ug=Us , mgh=(ktotalx2)/2. Plug in values for mass, force due to gravity, height, and x
(length of distance Barbie is wanted to fall). Solve for ktotal. This value of k is the total
spring constant needed to drop Barbie the desired distance x.
4. Since 1/ktotal=(1/k1)+(1/k2)+(1/kn)=(1/k1)*number of rubber bands (nr) in a parallel
sequence, ktotal=k1/nr. Plug in values for ktotal and k1. Solve for nr; this is the number of
