![]() Photogate measures the time from the first bob pass to the third, i.e., when the bob swings back through the photogate in the original direction. Place the photogate at the bottom of the pendulum swing. This same timing mode is used with an Ultra Pulley (Pulley.cmbl) or Bar Tape (Motion Timer Picket Fence.cmbl) From that distance data, velocity and acceleration can be calculated. As the picket fence moves through the photogate and the beam is alternately broken and unbroken, each event is given a distance, based on the known spacing of the picket fence. If you are using another or homemade picket fence, measure the distance from the leading edge of one dark band to the next.Īttach a picket fence to the object and set up a photogate so that the object will pass through it. (Sensor file uses the dark band spacing as the default distance.) If you are using a Vernier Picket Fence, Cart Picket Fence, or Ultra Pulley, no distance measurement is necessary. Motion Timer Picket Fence.cmbl, Pulley.cmbl, Cart picket fence.cmbl The object’s average acceleration is determined by dividing the change in speed from the first photogate to the second by the time elapsed between the two. The length of the object and the blocked times are used to calculate the object’s speed through each photogate. Three times are measured: the blocked time of the first photogate, the blocked time of the second photogate, and the elapsed time between the photogates. Set up two photogates so that the object will pass through both of them. The average speed of the object is determined by dividing the distance between the photogates by the measured time. Timing starts when the object breaks the beam of the first photogate and ends when it breaks the beam of the second photogate. The object’s speed (at the position of the photogate) is determined by dividing the length of the object by the blocked time. When the object passes through the photogate, it measures how long the beam is blocked. Set up the photogate so that the object moves through it. Measure the length of the object that will pass through photogate. For example, if you rolled a marble through the gate, you would need to know the diameter or secant of the ball that went through the beam. Note: If the length entered differs from the actual length of the object that passes through the beam, the speed measurement will be off. Save your modified sensor file under a new name in a location accessible to your students.If not, you may need to create your own user parameters and calculated columns to generate the data you want. In many cases, the sensor file will already provide the information you need. Click the Photogate and select “Set Distance or Length.” In the dialog box, enter the appropriate distance/length and the corresponding units. If no parameter box is on the page, the distance/length can be entered by selecting “Set Up Sensors” from the Experiment menu, then selecting your interface. Enter the distance/length into the appropriate parameter box, when applicable. Inaccurate distance measurements will lead to bad velocity and acceleration data.Ĭ. Take special care in measuring the appropriate distance/length. The Logger Pro sensor files for use with Photogates can be found in the Experiments>Probes & Sensors>Photogates folder.ī. Using the table below, determine which Logger Pro sensor file to open and which distance/length to measure.Ī.Below is an outline for some common data-collection setups. If you are writing your own lab, you will need to set the timing mode and enter the correct distance/length to get meaningful data. If you are doing an experiment from one of the Vernier lab books (e.g., Physics with Vernier), instructions for how to set up the Photogates with either Logger Pro or LabQuest are in the student versions of the experiment. For more information, see How can I use a Vernier Photogate to measure g? ![]() The default timing mode is Motion Timing, which is perfect for measuring g with the Picket Fence (PF). The mode you use depends on what quantity you want to measure. There are different modes for different types of experiments. If you are collecting data with Graphical Analysis or Graphical Analysis Pro, see this article.Īlthough the output of a Photogate is quite simple (blocked or unblocked), timing is determined by the photogate timing mode in the data-collection software. If you are collecting data using LabQuest App, see this article. ![]() The following information describes how to set up wired Vernier Photogates (VPG-BTD) when using Logger Pro 3 ![]()
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