Shivansh Shukla
Physics 50, sec 13
Lab 12 - Angular Momentum Collisions
Objective - The objective of this experiment is to observe and analyze one-dimensional
rotational collisions between a disk and a bar rotating about a common axis. You will test the law
of conservation of angular momentum and determine whether or not rotational kinetic energy is
conserved during the collision.
Think to Yourself - To measure the angular momentum of 2 different objects, first you need to
think about it in terms of before and after the collision. Since the angular momentum before will
be equal to the angular momentum after — if there are no extra forces acting on it, we can
calculate the angular momentum by putting the rotational sensor in place, I would measure the
velocity for the objects. Then I would use a scale to measure the mass for the disks. By using a
ruler, I can easily measure the radius. Since the disks will have different velocities, in the
beginning, we can use this part as before the collision and we can do the same thing for after the
collision.
Experiment -
Analysis 1.
2.
By looking at the data, one can tell that the collision started around 1.8 seconds and
ended around 2.3 seconds as you can see the drastic change in the graph where it drops
down suddenly.
3.
Procedure
a. Measure the radius of the disks by using the ruler.
b. Measure the mass of the disks by using the scale.
c. Place the disks on the rotational sensor and collect the data.
d. Solve for the momentum of the system.
e. Measure the length and width of the bar by using the ruler.
f. Measure the mass of the bar by using the scale.
g. Place one disk on top of the other and solve for momentum.
4. The sources of uncertainty would most likely come from the ruler and the scale as the
data can fluctuate on the scale or one cannot determine the length or width accurately.
Since there is friction involved in real life, the momentum should not be conserved and
the uncertainty should be greater.
5.
Report 1. For the analysis, there was a link on the instructions page that led me to a set of different
data points. So, I copied and pasted them on google sheets and created a scatter plot
graph for those points. The data shows the before and after collision data points and how
the momentum is changing. From this graph, we can tell if the momentum is being
conserved or not. After, I had to answer some questions that were given in the lab
instructions and solve some problems.
2.
Graphs
a. Angular momentum
b. Kinetic Energy
3. Both the angular momentum and energy is not conserved in this experiment. Energy and
momentum are being lost because of friction. There is friction between disks and the bar.