B. MEASURE THE SPRING CONSTANT FOR YOUR SPRING
In order to understand the SHM of a mass supported by a spring, you need to know the value of the spring constant k for the spring you are using. Check your spring to be sure it shows no signs of abuse, as deformed springs will not necessarily have constant k values.
B1. Draw a force diagram for a mass hanging vertically, supported by a spring. Assume the mass is in equilibrium (ie, no net force).
B2. If you replace the mass with a bigger mass, can the system still be in equilibrium? Does the spring force change? Does the spring extension increase, decrease, or stay the same?
B3. Attach one end of the spring to the support and the other end to the holder (holder mass = 50g) for the masses. Place the position sensor on the floor vertically beneath the holder. Open LoggerPro, and check that the position sensor measures the position of the holder and not the lab table or any other nearby object.
B4. Now, record the position of the holder through LoggerPro. What is the position uncertainty? (In this lab, there is no uncertainty for mass).
B5. Now add a 20 gram weights (you can assume this value is exact) to your holder, and record the holder's new equilibrium position and its corresponding uncertainty. Increase the mass by another 20 g, and repeat the process above. Do not add more than 80 g to the holder.
B6. Make a graph of force vs. holder height, and include error bars on your plot (ask your TA if you're unsure about how to do this). Draw the best straight line through your points and from the slope of the line calculate the spring constant.