# Ch4 HW1 - WebAssign Ch4 HW1 (Homework) Current Score: 39...

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Ch4 HW1 (Homework) Arthur Barfield PHYS 2211, section M, Fall 2008 Instructor: Jennifer Curtis Web Assign Current Score: 39 out of 39 Due: Monday, September 15, 2008 09:00 AM EDT Description Stiffness of interatomic bond; Young's modulus; compression forces Note that the multiple-choice question has only one submission, so think carefully. Instructions Reading: Sec. 4.5-4.7 The due date for this assignment is past. Your work can be viewed below, but no changes can be made. 1. [MI2e 4.X.3a] 2/2 points You hang a mass M from a spring, which stretches an amount 8 mm. Then you cut the spring in half and hang the same mass M from one half. How much does the half-length spring stretch? stretch = 4 4 mm A spring has stiffness 60 N/m. You cut the spring in half. What is the stiffness of the half-length spring? k s = 120 120 N/m 2. [MI2 04.X.03] 2/2 points If a chain of 30 identical short springs linked end-to-end has a stiffness of 260 N/m, what is the stiffness of one short spring? k s = 7800 7800 N/m 3. [MI2 04.X.04] 2/2 points

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50 identical springs are placed side-by-side (in parallel), and connected to a large massive block. The stiffness of the 50 -spring combination is 22000 N/m. What is the stiffness of one of the individual springs? k s = 440 440 N/m Solution or Explanation N side-by-side (parallel) springs, each stretched the same amount s , exert a total force N*k s *s , so effectively they act like a single spring of stiffness N*k s . One spring has 1/ N the stiffness of the combination.
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## This note was uploaded on 04/19/2010 for the course PHYS 2212 taught by Professor Kindermann during the Spring '09 term at Georgia Institute of Technology.

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Ch4 HW1 - WebAssign Ch4 HW1 (Homework) Current Score: 39...

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