Physics 8
Name____________________
Chapter 12.3
Date Started ________________
Marble container number ___
Due Date __________ Period ____
Lab: Conservation of Momentum
Objective: to investigate the concept of conservation of momentum using a ramp
and marbles.
Materials: triple beam balance, 3 marbles (two large-same size (one has a black
dot), one small marble), stopwatch, two -1 meter tracks, assortment of books to
prop up track, meter stick
Equations: P = m v
%𝑒𝑟𝑟𝑜𝑟 =
Pin = Pout
min vin = mout vout
𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑓𝑟𝑜𝑚 𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒
𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒
v=
𝑥 100
𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒
Something
to stop the
marble
Diagram of set-up:
Input Marble has a big dot
10cm height,
prop up the
tilted track
with books
Output Marble
2cm gap between the tracks so the
Input marble stops in this gap
Procedure:
1) Gather all materials; keep the three marbles securely on table.
2) Identify each marble. One large marble is the Input Marble (has a big dot), the
other is the Output Marble. The small marble will be used near the end of the
lab.
3) Set up the 1 meter ramps according to the diagram of set-up.
4) Record all data on the Data Table when each step asks to measure. Design an
appropriate title for the Data Table.
5) Measure the mass of the Input Marble to the nearest 0.1g. Convert the
measurement to Kg to the 0.0001kg place.
1
Physics 12.3 Conservation of Momentum Lab 11.2014
6) Steps to find the momentum of the Input Marble:
a. Confirm that the input distance track is 1.0m.
b. Measure the time of 3 Input Marble trials to the nearest 0.01s.
c. Calculate the average of the 3 Input Marble trials to the nearest
0.0001s.
d. Calculate the average velocity of the Input Marble to the nearest
0.0001m/s. Show the E.S.A. on the Data Table. Use v = d/t.
e. Calculate the momentum of the Input Marble to the nearest
0.0001kg∙m/s. Show the E.S.A. on the Data Table.
7) Steps to find the Output Marble mass:
a. Confirm that the output distance track is 1.0m
b. Confirm that the diagram of set-up is proper, especially the 2cm gap.
c. A “good trial” is when all of the momentum of the Input Marble is
transferred to the Output Marble and the Input Marble stops at the gap
while the Output Marble moves down the output track.
d. Practice step “6.c” so you have consistent trial times. Measure the
time of 3 Output Marble trials to the nearest 0.01s.
e. Calculate the average of the 3 trials rolling time of Output Marble to
the nearest 0.0001s.
f. Calculate the average velocity of the Output Marble to the nearest
0.0001m/s. Show the E.S.A. on the Data Table.
g. We will assume that this set-up is a closed momentum system where
momentum input is equal to momentum output. Since you have
calculated the Input Marble momentum you also know the Output
Marble momentum.
h. Calculate the Output Marble mass to the nearest 0.0001kg. Show the
E.S.A. Use (min vin = mout vout ) Rearrange the equation and solve for
mout. This calculated mass is used in procedure step #8.
i. Measure the mass of the Output Marble to the nearest 0.1g. Convert
the measurement to Kg. This measured mass is the “accepted value”
that will be used in procedure step #8.
2
8) Calculate the % error of the Output Marble mass calculation compared to
the “accepted value” of mass to the nearest 0.0001%. Show the E.S.A. If
your % error is greater than 30%, Re-measure your data.
Conclusion Questions: Complete these questions as well as all portions of P.4 data
table.
1. Describe two sources of error that lead to your answer for step 8.
Source#1:_____________________________________________________
_____________________________________________________________
_____________________________________________________________
__________________________________________________________
Source#2:_____________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
2. Predict the output velocity, if a smaller output marble were used. Explain
your reasoning. Use the smaller marble in another set-up. Show your results.
Prediction:____________________________________________________
_____________________________________________________________
_____________________________________________________________
Reasoning: (Include: p,m,v)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Results (include E.S.A., 0.0001m/s):________________________________
Use: v = d / t
3
DATA TABLE TITLE: ___________________________________
Mass of Input Marble _______ g _______kg
Input distance ________m
Input Marble:
Trial 1 ______s Trial 2 ______s Trial 3 ______s
Input Marble average time _____s
Input Marble average velocity E.S.A.
Input Marble momentum E.S.A.
Output distance _______m
Output Marble:
Trial 1 ______s Trial 2 ______s Trial 3 ______s
Output Marble average time _____s
Output Marble average velocity E.S.A.
Output Marble calculated mass E.S.A.
Output Marble measured mass ______ g _____ kg
% error of the Output Marble mass calculation:
4