Hooke’s Law Lab
NAME:_______________________
DATE:_____________PERIOD:___
Objective: To study Hooke’s law. To use Hooke’s law to find the spring constant of a given spring. To use
Hooke’s law to find the weight of an unknown mass.
Materials: spring; ruler; five 5.00 g masses; a plastic cup; 2 paper clips; tape; unknown mass
Procedure:
1) Tape a paper clip to your desk and hang the spring with the plastic cup attached to it from the paper clip.
2) Measure and record the length of the spring with the cup hanging from it.
3) Place the masses in the cup and record the new length of the spring.
4) Record the letter of your unknown mass.
5) Place the unknown mass in the (empty) cup and record the length of the spring.
Data:
1. Length of unstretched spring (with cup hanging):______________
2. Total Length of Spring
MASS
LENGTH OF
SPRING
0.00500 kg
0.0100 kg
0.0150 kg
0.0200 kg
0.0250 kg
Unknown
Calculations: (Read Calculations section):
TOTAL CHANGE IN
LENGTH OF SPRING (Δx)
FORCE OF SPRING (Fs)
?XXXXXXXXXXXXX?
3. Letter of unknown mass:_____
Calculations:
1) Find the total change in the length of the spring for each mass added (length of spring – length of
UNSTRETCHED spring). Record the change in length in the data table above.
2) Find the force of the spring for each mass. (Since acceleration = 0, the upward force of the spring must
have the same magnitude as the downward force of gravity. Therefore Fs = W, and W = mg.)
Analysis:
1) Draw a graph of the spring force (vertical axis) vs. change in length of the spring (horizontal axis) on the graph
paper provided. Draw a line of best fit. Make sure to label the axes, with units, and to include a title.
2) Hooke’s Law states that, since the graph is linear, Fs = kΔx. Therefore, k = Fs /Δx, where k is the spring constant.
Graphically, k is the slope of the Fs vs. Δx graph. Find k by choosing two points on your line of best fit (NOT two data
points) and calculating the slope. Show your work below (remembering units!). Extra credit: In addition, use a
computer or graphing calculator to create another graph with a statistically calculated line of best fit.
3) Calculate the mass of the unknown mass, showing your work below. (Note: you will need to use your answer from
Analysis #2.)