Physics 152L Introduction
In Physics 152L you will perform seven physics laboratory experiments (E1 through E7) plus one Measurement Analysis exercises (MA). The schedule of activities and experiments is listed below in chronological order.
- Orientation/E1: The odd numbered sections are sceduled for the first week while the even numbered sections are scheduled for the second week. For the first half of the class you will meet and receive information from your laboratory GTA. For the second half of the class you will use an ultrasonic ranging system to find the relationship between position, velocity, and acceleration for a cart on a track.
- MA: Measurement Analysis. The MA prelab covers significant figures, uncertainties in reading scales and digital readouts, discrepancy and agreement. Propagation of uncertainties is based on a worst case scenario, which is compatible with the mathematical knowledge expected for Physics 152. MA also covers graphical analysis and least squares fitting using spreadsheets and software plotting packages are discussed. A graphical technique to find the dependence of a variable on another is presented. The MA exercises are done on CHIP152L and are due at the beginning of experiment E2, along with the MA graph and the E2 prelaboratory exercises.
- E2: Using a video based data acquisition system the motion of objects in 2 dimensions is explored. Various objects are tossed, dropped or spun and their position versus time is found from digital movies of their motion. Specifically the motion of projectiles and uniform circular motion are studied.
- E3: Using an inclined air track g is measured. In the second part of the experiment small, powerful magnets are attached to the legs of an air track glider to give a retarding force that is a function of velocity. When a moving glider on a tilted air track reaches a terminal velocity, the retarding force is equal to the component of gravitational force parallel to the air track. By varying the tilt of the air track, the dependence of the retarding force on velocity is found. The velocity dependence of the air drag on a falling coffee filter is also measured.
- E4: E4 investigates conservation of energy using a glider being pulled on a level air track by a hanging weight and then by a stretched spring is investigated. Using techniques from MA, results are graphed with a software package and a spreadsheet is used to do a least squares fit to determine the spring constant.
- E5: Conservation of momentum, Newton's 3rd Law, and The impulse momentum theorem. The instrumentation in this experiment consists of two force probes, each mounted on one end of a rolling cart, and two ultrasonic ranging systems such that two forces and two positions can be measured simultaneously. Conservation of momentum is tested. Similarly Newton's 3rd law is observed as the two force probes push against each other. Also the impulse momentum theorem is tested that states that the impulse is equal to the change in momentum in a general one-dimensional collision between two carts.
- E6: Rotation dynamics. In the first two parts of this experiment students are part of the apparatus. Using barbells and spinning bicycle wheels, the forces that occur in order to conserve angular momentum are experienced. In addition, an "angular collision" between the rotating platform and a polycarbonate disk dropped onto it is studied to test whether angular momentum is conserved; results for this part generally agree with expectations to the 1% level.
- E7: Simple harmonic motion. The dependence of the period, which is the time taken for one complete cycle of oscillation, of a torsional pendulum on amplitude of oscillation, stiffness of the wire, and moment of inertia of the pendulum are investigated. In order to determine the moment of inertia of the pendulum, an additional object, consisting of two brass cylinders, of known moment of inertia is used.
- Record Check. This is a final session in which you will pick up your graded lab report for experiment E7 and verify all of your laboratory scores.
It is essential that you are prepared to do a scheduled experiment when you arrive for class. To motivate you to read and understand the relevant parts of the laboratory, you are required to complete prelaboratory exercises before the beginning of each laboratory experiment. These exercises are worth 25% of the credit for an experiment and are worthless after the beginning of a class. To reduce the grading load and associated bookkeeping and to give students instant feedback, prelaboratory and MA exercises, except for the graph associated with MA, are handled by Computerized Homework in Physics (CHIP), a World Wide Web-based human-computer interface. This system is presently handling both the recitation homework and prelaboratory exercises for Physics 152.
Fifteen experimental stations have been set up in Room 18 of the Purdue University Physics Building. Ultrasonic transducers, strain gauges, and dual optical switches have been interfaced to Macintosh 350 MHz G3 minitower computers to measure position, forces, and angular position. Data are passed to and from the computer through National Instruments PCI-1200 multifunction input/output (I/O) boards. Data acquisition, reduction, and display software has been developed under the framework of National Instruments LabVIEW 5.1. Graphical output is printed by a Hewlett-Packard 8150DN LaserJet printer in the laboratory room. The laboratory is operated jointly by the Department of Physics and the Instructional Computing Center (ICS).
