MAKE 2 COPIES OF COVER PAGE
PHYSICS 23 LABORATORY E5: CONSERVATION OF ANGULAR MOMENTUM Spring 07 NAME:
DATE:
Partner’s Name: Laboratory Instructor:
Laboratory Section:
Recitation Instructor:
Recitation Section:
You will be submitting this laboratory report electronically using BlackBoard. However, you will PRINT a cover page for each member of your team. Your laboratory instructor will show you how to submit the report electronically. The cover page with grade will be returned to you, as usual, by your recitation instructor. Your report with comments will be returned to you by email.
OBJECTIVES: 1. Use rotational collisions to study the conservation of angular momentum when two rotating disks interact.
Reading: Introduction: What is required in order for angular momentum to be conserved?. Apparatus: PASCO Rotational Dynamics Apparatus with DataStudio. GIVEN: Moment of Inertia of Aluminum Disk = IAL = 0.00375 kg-m2 Moment of Inertia of Stainless Steel Disk = ISS = 0.0107 kg-m2 BOTH SS Disks have the same moment of inertia. Procedure: Make sure the air supply is on to your apparatus. NEVER rotate the apparatus without air, as this will damage the air bearing. Make sure the bottom disk is oriented so that the bearing side is down and a gap appears next to the axle on the top side of the disk:
DISK
Set up DATA STUDIO to use the rotational dynamics apparatus. Attach a table and a graph to
plot the angular velocity. Do this for both the upper and lower disks on the same plot. The upper disk is the one with the yellow tape on the plug. Set rate to 2 samples per second. As we want both disks to rotate, make sure the pinch cock at the side is closed. With only the two disks, put the “pin” with the black handle down the center of the upper disk. When this pin is in place, there is an air bearing between the upper and lower disks, as well as between the lower disk and the apparatus base. Removing the pin with a quick motion, allows the upper disk to “collide” with the lower disk by removing the air bearing between them. Perform at least three different collision experiments and describe what you did. There is a stainless steel disk which can be used as the top disk, instead of the aluminum disk. This allows you to change the mass of one of the colliding disks. Record the initial and final angular velocities and other information needed to calculate the moments of inertia of the disks. Measurements: (The table is an active EXCEL Worksheet). You can do your calculations in it.) You will need to enter calculations into table except for the conversion of omega from degress/s to r/s. RUN #1: Describe your collision and be sure to indicate the sign of ωINITIAL and ωFINAL Moment of I ωINITIAL ωFINAL LFINAL LF - LI ωI rad/s ωF rad/s LINITIAL Upper Disk Lower Disk TOTAL
0 0
K INITIAL
K FINAL
0 0
KF - KI
Upper Disk Lower Disk TOTAL
RUN #2: Describe your collision and be sure to indicate the sign of ωINITIAL and ωFINAL Moment of I ωINITIAL ω FINAL LFINAL LF - LI ωI rad/s ωF rad/s LINITIAL Upper Disk Lower Disk TOTAL
0 0
KINITIAL
KFINAL
0 0
KF - KI
Upper Disk Lower Disk TOTAL
RUN #3: Describe your collision and be sure to indicate the sign of ωINITIAL and ωFINAL Moment of I ωINITIAL ωFINAL LFINAL ωI rad/s ωF rad/s LINITIAL Upper Disk Lower Disk TOTAL
0 0
K INITIAL Upper Disk Lower Disk TOTAL
Analysis:
K FINAL
KF - K I
0 0
LF - LI
Use the tables above to calculate whether angular momentum was conserved and whether rotational kinetic energy was conserved for each of the three collisions you measured. Conclusions: For each of your collisions, was angular momentum and rotation kinetic energy conserved?