Measurements
 Activity
|
The goal of this activity is to determine the spring constant for Spring #1 and learn a bit about Hooke's Law along the way. The activity is broken into two parts. In the first part of the guided activity you will measure the displacement of the bottom of Spring #1 when a mass is attached to it. The second part you will analyze your results. Any time you need help click on the green "Show Help" button.
- Make a data table in your notebook with headings called mass, weight, and displacement (see below) assuming that each group member will measure at least one mass.
- Move the reference line so that it is at the bottom of Spring #1.
- Hang the 50 g mass on Spring #1.
- Record the mass in your data table.
- When the mass has come to rest measure the displacement of the bottom of the spring with the ruler.
- Record the displacement in a data table with headings called mass, weight, and displacement. Make sure to record the units.
- Repeat steps 2 through 5 with a 100 g mass and then the 250 g mass.
|
|
|
<flash>file=MassSpringLab2.swf|width=90%|height=500|bgcolor=#ffffff;|quality=best</flash>
Example data table:
| Mass(g) |
Weight (N)
|
Displacement (cm)
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
Multichoice Question
What answer best represents the displacement of the bottom of Spring #1 in metres when the 100 g mass is hanging on it and at rest?
| (a) 9.8 m |
(b) 9.8 × 10−2 m |
(c) 4.9 × 10−2 m
|
Reflection
Reflection
|
Converting measurements to SI units can be useful when dealing with quantities that have complex units.
The best answer to the question above is (b) because the magnitude and units match the theoretical values. If you measured between 9.9 × 10−2 m and 9.7 × 10−2 m you are doing well.
|
Analysis
| Activity
|
| You have completed the first part of the activity and are ready to analyze the data.
Proceed with the following instructions:
- Each person should calculate the weight in Newtons, N of several masses in your data table so that each mass has a corresponding weight.
- Record the results in the weight column of the data table.
- Discuss the best method for calculating the weight and then record a sample calculation in your notebook.
- Calculate the average displacement for each mass that was measured multiple times.
- Record the average displacements in the data table.
- Plot a Displacement vs Weight graph for the individual data points.
- Draw a best fit straight line through the individual data points.
- Calculate the slope of the best fit straight line.
- Record the slope with its units in your notebook.
- Repeat steps 6 to 9 for the average data.
- Hooke's Law states that the force on the mass due to the spring is directly proportional to the displacement of the spring. This looks very similar to the slope except that you measured the weight not the force due to the spring. Do you remember the relationship between the weight and the force due to the spring from the first multichoice question? Record the relationship between the weight and the force due to the spring.
- Determine the spring constant for Spring #1 for the individual.
- Record the spring constant in your notebook for both the individual data and the average data.
- Discuss your results and record your findings in your notebook.
|
|
|
Activity
