Investigation 5B: Hooke’s law

Essential questionsHow are force and displacement related when stretching a spring?
The physics underlying a spring can be expressed by a straightforward relationship between how much the spring is extended (or compressed) and the restoring force the spring exerts. This relationship is known as Hooke's law. In this investigation you will measure force from the spring, and spring deformation (spring deflection) using the force and position sensors on the Smart Cart.
Part 1: Extension and spring force

  1. Set up the equipment like the picture using the loosest of the three springs.
  2. Open the 05B_HookesLaw experiment file in your software, and then connect your smart cart using Bluetooth.
  3. In your software, zero the Smart Cart force sensor while nothing is touching the hook.
  4. Begin recording data, and then roll the cart backward (extending the spring) about 10 cm and hold it in place. Click the check mark to record your first data point.
  5. Keep pulling the cart backward and record four more data points at four different deformation lengths (any lengths will work as long as they are in order from shortest to longest).
  6. Stop recording data, and then copy your data into a table. Sketch a copy of your graph.
Part 2: Stiff and loose springs

  1. Repeat the experiment using the medium and stiff springs.
  2. Tabulate your data, and then sketch the graphs for each spring.
  1. When you stretch the stiffest spring by hand, how does it feel or respond that is different from the loosest spring? In supporting your answer, use data from your investigation.
  2. How does the extension of the stiffest spring compare to the loose one for the same applied force?
  3. What are the slope values of the three graphs? (Include units in your answer.)
  4. What physical quantity do the slopes of your graphs represent? Why?
  5. What is the spring constant of each of the springs? (Include units in your answer.)
  6. Use your data to determine the force each spring would exert at these other deformations.

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