Physics 4AL: Mechanics Lab Manual1

UCLA Department of Physics & Astronomy

May 12, 2017

1This manual is an adaptation of the work of William Slater by W. C. Campbell, Priscilla Yitong Zhao, Julio S. Rodriguez, Jr., Chandler Schlupf, and Anthony Ransford Abstract

Physics 4AL is designed to give students an introduction to laboratory experiments on me- chanics. This course is intended to be taken after completion of Physics 1A or 1AH and concurrently to the student taking Physics 1B or 1BH. We will be experimentally investigat- ing some of the most foundational concepts in physics, including gravity, energy, momentum, harmonic oscillation and resonance. These concepts are the basis for the classical motion of everything from electrons to galaxies. There are a lot of “science skeptics” in the world; I invite you to come to class with a critical eye and to experimentally test whether we, your instructors, have been lying to you all these years! i. Introduction to the Data Acquisition (DAQ) system

A crucial part of modern experimental physics is the use of computers to aide in data acquisition and experimental control. Computers can allow us to take data faster, more accurately, and with far less tedium than was possible before their integration into the laboratory. It is therefore crucial that an introductory physics laboratory course include the use of computer-aided data acquisition (DAQ), and we will be using the DAQ throughout the course to allow us to focus on the physics. This chapter will introduce the system we will use and can be regarded as a user manual and general reference for later experiments. i.1 PASCO DAQ System: Capstone and the 850 Uni- versal Interface

Figure i.1: The PASCO 850 Universal Interface

The data acquisition (DAQ) system we will use in this course is produced by PASCO Scientific for instructional lab courses. The software is called Capstone, and provides the

1 Figure i.2: The default startup screen for PASCO Capstone version 1.0.1. You may be using a slightly newer version that looks a little different, but the basics should be the same. communication with the hardware interface. This guide is based on PASCO Capstone 1.0.1 and the PASCO 850 Universal Interface, which is the piece of hardware that connects the computer to your instruments, shown in Figure i.1. i.2 Startup

To begin, ensure that the 850 is connected to the computer (via USB) and power it on by pressing the power button on the front if the 850 is not already on. If the unit is powered up and connected to the computer, the power button will be backlit in blue and the connection indicator light just below the power button will be illuminated in green. If you encounter problems with either of these, check that cables have not come loose or ask for help from your TA. Next, start the Capstone program, which has a logo that looks like, well, a capstone. Once running, the program should look something like Figure i.2.

2 Figure i.3: Clickable Hardware Setup screen shot

If the Tools palette on the left is missing, click the gear icon in the upper left (“Change properties of current page and Tools Palette”) and check Show Tools Palette under Page Options. You can also right-click on the gray Capstone desktop and check Show Tools Palette. The same thing goes for the Controls and Displays palettes.

If your palettes are not shown on the screen, right-click the gray desktop and select the appropriate palette.

i.3 Configuring Hardware

To set up the hardware for a specific experiment, click on the Hardware Setup icon in the Tools palette. If the 850 interface is turned on and is communicating with the computer, this will bring up a clickable picture of the front panel of the 850 interface, as shown in Fig. i.3. The yellow circles are clickable and will enable you to tell the computer what hardware is attached to each connector on the 850 interface. Clicking on the yellow circle will bring up a drop-down menu showing the possible types of hardware con