Purpose
Measure the translational acceleration of a object falling from a pulley (as
illustrated in the figure below), and
Use the measured acceleration to analyze the validity of assumption that the
pulley exhibits rotational inertia consistent with a disk (I = ½ MR2).
illustrated in the figure below), and
Use the measured acceleration to analyze the validity of assumption that the
pulley exhibits rotational inertia consistent with a disk (I = ½ MR2).
Equipment
Pulley, hanging mass, motion detector with CBL data acquisition system.
Procedure
In this lab we set up a pulley above the ground by clamping a metal rod to a table with a pulley system attached the top of the rod. The pulley hung some distance above the ground. A thin string was rapped around the pulely with an action figure tied to the end of the string. A motion detector was placed below the action figure. An index card was taped to the bottum of the action figure so that the motion dectector could read the falling object better. The action figure was dropped about the pulley. while the motion dectector recieved data while it fell. Next the mass of the action figure, index card and tape together was measured along with finding the masss and radius of the pulley.
Data
Data Analysis
The graph above represents the distance the action figure falls relative to time, with the slope of the curve being (distance/time) which is the velocity of the action figure at that particular time.
Conclusion
In this lab, the purpose was to use the exquipment given to run an experiment and solve for the translational acceleration and then to use this number and the other values to come up with the interia of the falling mass from a pulley. Next was to compare this value with the rotational inertia of a disk and compare the two. After solving for the percent error of the comparing inertias from the data it is seen that there is quite a large margin of percent error. This could be logical because there are many different variables that could cause this. Some problems could have been the pulley's radius declining as the action figure drops, the friction in the pulley, human error, or possibly en error in the electronics like the motion detector. All of the following variables should be taken into consideration when dealing with the given percent error.