Remember to hit the "reload/refresh" button to see changes
made to this page.
We will be doing "Lab 12", exactly as described in the lab manual.
Remember to make a note during the lab about which of the main results provides specific quantitative support for your answer to this question.
Read the theory for "Lab 12" (pages 127 to 128) in the lab manual before answering the questions on LON-CAPA.
(Hint: Read the hint given in the next-to-last problem.
You have a built-in check since you already know one of the two solutions. If your result from the quadratic formula does not include that one, you have made an error.)
You should use the adjustments available in the setup to position the meter stick so it is easy to read the length of the spring, particularly when it is fully extended and/or in motion. You might make some trial runs with the 500 g mass to see how it will work in various configurations. Be particularly careful to be sure you are using a point on the bottom of the spring that can be read consistently when the spring is stretched. See the picture at the bottom of this page.
There are various tricks that can be used to make an accurate measurement of position while the mass is in motion. All of them require repeated measurements for the same initial conditions, so care in setting the starting point the same way every time is very important. One trick is to use your finger as a placeholder near where you think the end of the spring stops while making repeated measurements. Anticipating where it will stop helps guide your eye and makes it easier to fine-tune your reading. Another, helpful when dropping the mass, is to use a horizontal ruler to locate where the bottom of the mass stops. Once sure of that, you can pull the mass down to this position and read where the bottom of the spring is located.
The photo below shows the apparatus as it should look when you arrive.
When you are done with the lab, you should put it back the way you
found it so then next group will also find it looking like this.
The balance is provided so you can check the masses of the masses you will use. They are not all the same, with many being a bit light due to paint chipping off when mishandled. Ignoring these small differences can introduce a significant percentage error for the lighter masses you use and bias your results.
The photo below should give you some idea of the issues you will
face when making a measurement. Here you see a fairly small mass
on the spring, and I have added some lines in blue to help identify
the key features in the photo without obscuring the spring itself.
Contact me if you have any questions.