Guided Activity

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.

1. Move the friction slider to the right so it points at "lots". This will cause the mass to come to rest the quickest. Can you think of a reason why? Record your thoughts in your notebook.
2. Make a data table in your notebook with headings called mass, weight, and displacement (see below).
3. Move the reference line so that it is at the bottom of Spring #1.
4. Hang the 50 g mass on Spring #1.
5. Record the mass in your data table.
6. When the mass has come to rest measure the displacement of the bottom of the spring with the ruler.
7. Record the displacement in a data table with headings called mass, weight, and displacement. Make sure to record the units.
8. Repeat steps 2 through 5 with a 100 g mass and then the 250 g mass.

Special thanks to the Physics Education Technology PhET Team

Masses and Springs Simulation
<flash>file=MassSpringLab2.swf

Example data table

Mass (g) 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?
• 9.8 m
• Incorrect, take a closer look at the units on the ruler.
• 9.8 × 10−2 m
• Absolutely correct!
• 4.9 × 10−2 m
• Incorrect, you have the correct order of magnitude but you are off by a factor of two. Try your measurement again.

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.