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Unformatted text preview: In class you learn about Hookes Law, which states that a force applied to a spring causes its length to change in a manner so that it stretches an amount exactly proportional to the applied force = o + 1 k F where is the length when the force is applied, o is the length when no force is applied, and k is the spring constant. Notice that in the above formula, that the amount of stretching is strictly proportional to the force. Such objects are said to respond linearly to the force. Nonlinear behavior would arise if the length was not exactly proportional to the force, say it behaved as - = F/k + F 2 /k 2 . Also the amount the spring stretches does not depend on how the force was applied, or whether the force has been repeated applied and removed. Such effects can be important in some cases. We then say the material exhibits plastic or brittle behavior. Procedure Apparatus: Spring, mass hanger pan, spring support stand, meter stick, position indicator, (these are collectively called a Jolly Balance), a set of slotted masses, triple beam balance. 1. Your instructor will demonstrate how to use the position indicator to determine the elongation of the spring. 2. Attache the spring to the hanger rod and attache the mass hanger pan to the spring. 3. If the coils of the spring are not separated, add just enough mass to the hangar to ensure the coils are separated. This mass (if any) will stay on the pan at all times, but is not counted as part of the added mass in the steps below. 4. Use the triple beam balance to determine the total mass of the hanger rod, hanger pan, and any extra mass added in step 3. 5. Reattach the hanger to the spring. Measure the starting position of the hanger. 6. Take eight 20 g masses and measure their masses. Compare the average mass to the stamped value. Are they equal? 7. You will now add masses in amounts of 20 g each to the hanger and measure the amount the spring stretches. Each time you add a mass, slowly lower the hanger untilamount the spring stretches....
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