Physics 109 - Hooke's Law
This experiment is a chance to refresh your skills from last
As a review of last term, work in groups of 4, on the boards or
on large paper sheets, and sketch a flow diagram that ilustrates
the steps that you gor through when doing an experiment.
After we discuss the flowcharts, regroup to discuss why we do
these things when trying an experiment. Write these reasons in
your lab notebook.
PART III - Uncertainty Problem
(work in pairs)
The following problem
will help you with an uncertainty calculation needed in the
Consider a situation where you have measured a distance of 1.55 cm on an analog scale with 0.1 cm divisions. You decide that the maximum value it could possibly be is 1.60 cm and the minimum is 1.50 cm.
What do you report as the uncertainty?
Next consider a similar measurement of 2.75 cm, with the
same uncertainty, and you need to subtract these two distances.
What is the difference in the distances? What is the uncertainty
in the difference after you do this subtraction?
Hooke's Law is a description of an ideal spring that says the
stretch in the spring is linearly related to the force applied : F = kx, where k is called the spring
In MKS, what are the units of k?
Using the apparatus at your desk
provide a very high-quality measurement of the spring constant
using Hooke's Law. (Hint: Your measurements of distance
should be taken more precisely that just to the nearest mm.)Your
final result should include a graph of stretch versus mass with a best fit line that
goes through the origin, a plot of residuals from the fit, and
your best estimate of the value of the spring constant in SI
units. Remember to record which spring set-up you use, since you
will want to use the same one for another experiment later.
2 marks flow chart participation, and an explanation in your notebook
2 marks for uncertainty problem
10 marks for a high quality determination of the spring
don't forget to: