AP Physics 1 Lab
Spring Constant
Objective
To determine the spring constant for a spring using Hooke’s Law and the period of
oscillation
Materials
List the materials you will used in the lab. You may want to use a sketch showing the
apparatus
Data
Describe 1) the data you will collect (what measurements will you make?) 2) how will
you collect the data (what tools will you use?) and 3) how you will use the data. Show any
equations you will use to make calculations. Record the data in a data tale in your notebook. It
is not necessary to write an entire procedure.
Procedure
Finding the spring constant using the Hooke’s Law
1.
Find the mass (in kg) of the inertial balance. Record this value in Data Table 1.
Divide this mass by two. This is the approximate mass of the platform of the
balance. Record this value in Data Table 1. This is also the value of the mass for
Trial 1.
2.
Set up the inertial balance as shown in the demonstration model. Use a pair of
rulers to find the vertical distance (in m) the mass bends the spring. Record this
value in Data Table 1 for Trial 1.
3.
Complete Trials 2-5 by adding 0.100 kg, 0.200 kg, 0.300 kg and 0.400 kg to the
platform. When recording these masses in Data Table 1, be sure to include the
total mass by including the mass of the platform. Record the vertical
displacement for each mass.
Finding the spring constant using the period
1.
Change the setup of the inertial balance so it will oscillate horizontally. Tape
0.100 kg on the platform. Record the total mass (including the platform) for
Trial 1 in Data Table 2.
2.
Pull the platform to one side and allow the balance to oscillate. Find the time
for 20 oscillations. Record the time in Data Table 2. Repeat the procedure
twice more for Trials 2 and 3. Record the time for 20 oscillations for each trial
1
3.
Repeat Procedures 1 and 2 to complete Trials 4-6 by adding 0.200 kg to the
platform. Complete Trials 7-9 by adding 0.300 kg to the platform. Complete
Trials 10-12 by adding 0.400 kg to the platform.
Calculations
1.
Find the Force (in N) on the spring by calculating weight of the mass for each
trial in Data Table 1. Graph Force vs. Displacement for you data in table 1. Draw
a line of best fit for your data. Find the slope of the line and record this value as
the spring constant k for the inertial balance using Hooke’s Law.
2.
Find the average time for each mass. Use the average time to find the period
(time for a single oscillation) for each mass. Find T2 (in s2) for each period.
Record each of these values in Data Table 2.
3.
Graph T2 vs mass. Draw a line of best fit for your data. Use the slope of the line
to find the spring constant k of the inertial balance using the period. Find
absolute value of the relative difference of the spring constant using the two
methods.
1.
How would a stiffer spring change the value of the spring constant? How would
this change affect the values for the elastic potential energies for a compressed
or stretched spring? Which variable, the spring constant or the displacement
has the greatest effect on the elastic potential energy? Explain.
2.
As the spring oscillates, what is the position of the inertial balance when it has
maximum elastic potential energy? Describe the position of the inertial balance
when the elastic potential energy is zero.
3.
At what point is the velocity of the oscillating inertial balance greatest? What is
the net force on the mass at this point?
4.
At what point is the restoring force on the mass the greatest?
5.
Describe a position during the oscillation that could be used to calculate the
total mechanical energy of the mass.
Analyze
2
AP Physics 1 – Spring Constant
Data Table 1 – Hooke’s Law
Mass of Platform (kg) =
Trial
Displacement x
(m)
Mass (kg)
Force (N)
1
2
3
4
5
Spring constant k =
Data Table 2 – Period of the Spring
Trial
Mass (kg)
Time (s)
Average Time (s)
1
2
3
4
5
6
7
8
9
10
11
12
Spring constant k
Relative difference in spring constants by the two methods __________
3
Period T (s)
T2 (s2)