Practical 1 Measuring Acceleration
Introduction
his practical is designed to help the student understand the ideas of instantaneous velocity, displacement and the equations of motion with constant acceleration. In addition students gain more practice using the apparatus, manipulating data and plotting graphs.
In this experiment a trolley is sent down a ramp. It's velocity is measured as it passes through a lightgate after different displacements. Students have to plot a graph of v² against s including custom error bars. Full instructions on how to do this are given.
Assessment
Too much information on how to process the data is given on the worksheet so this practical is not used for assessment, however the reports are marked using the criteria and students are given feedback to help them understand how the assessment works. This can be a bit demoralising since at this stage students don't really know what is required so they tend to score quite badly.
Feedback is given on the following criteria:
DCP
The table should be properly constructed with headings, units and uncertainties. All values in a column should have the same significant figures. There should be at least 6 different heights and each reading should be repeated 4 or 5 times.
The velocities must be squared correctly and the uncertainties propagated, the number of sig figs in the average velocity squared column shouldn't exceed the uncertainty.
A graph of velocity squared against distance traveled should be plotted, this should be labeled including units. Custom error bars should be drawn and a best fit line plotted automatically. Hand placed steepest and least steep lines should also be included
CE
The conclusion should include a value for a including uncertainties calculated from the steepest and least steep gradients, students should say if theit value is reasonable. Comments should be made about the linearity of the graph. Weaknesses of the method should be pointed out and ways these could be addressed described.
Click here for a sample worksheet