Starter
A student records the motion of a spinning object and
obtains a theta vs. time graph. The computer gives a fit:
q(t) = At2 + Bt + C where A = 6.50 , B = .001
and C = 0.00
What is the experimental value of the angular
acceleration a?
(1/2)a = 6.50
so a = 13.0 rad/s2
Hint: consider
qf = qi + wit + (1/2) at2
Practice
Recall from the circular
motion study that:
qf = qi + wit + (1/2) at2
wf = wi + at
You will investigate these relationships.
Procedure
1. Connect the smart pulley to the Vernier interface.
Connect the interface to the computer.
2. Find the file” Smart Pulley Rotation Lab” on the K
drive under Davenport Physics and double click on it.
3. Spin your pulley and once it is spinning hit the green
collect button. You will have an angle vs. time graph (q vs. t)
and a Angular Velocity vs. time graph (w vs. t ).
Analysis
A. Obtain a theta vs. time graph. Fit a curve to your graph and sketch
the graph. Write down the equation for the fit on the graph.
B. Obtain a angular velocity vs. time graph. Fit a curve to your graph
and sketch the graph. Write down the equation for the fit on the
graph.
C. Find the experimental acceleration from your theta vs.
time graph. (Twice the coefficient of t2). Call this value
E1.
D. Find the experimental acceleration from your w vs. time
graph (the slope). Call this value E2.
E. Find the % difference between your two E1 and E2.
Questions
Write 1 paragraphs explaining the results
( your two graphs ) including an explanation of:
1. How you obtained the angular acceleration
from each graph.
2. How the graphs compare to the y vs. t graph and
v vs. t graph for free fall.
Lab Report Checklist
A. Cover Sheet
B. Two Graphs
C. Both accelerations and the percent difference.
D. Questions
E. Summary
EXIT
A student records the motion of a spinning object and
obtains an w vs. time graph. The computer gives a fit:
w(t) = At + B
where A = 8.50 and B = 1.00
What is the experimental value of the angular
acceleration a?