Chapter_8_solved_problems_Physics_1301

Chapter_8_solved_problems_Physics_1301 - Chapter 8 solved...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 8 solved problems 4. Picture the Problem : The physical situation is depicted at right. Strategy: Use equation 2 1 2 W kx = (equation 7-8) to find the work done by the spring, but caution is in order: This work is positive when the force exerted by the spring is in the same direction that the block is traveling, but it is negative when they point in opposite directions. One way to keep track of that sign convention is to say that ( 29 2 2 1 i f 2 W k x x = - . That way the work will always be negative if you start out at i 0 x = because the spring force will always be in the opposite direction from the stretch or compression. Solution: 1. (a) Sum the work done by the spring for each segment of path 1: ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 { } ( 29 ( 29 2 2 2 2 1 1 1 2 2 3 2 2 2 2 2 1 2 1 550 N/m 0 0.040 m 0.040 m 0.020 m 0.44 J 0.33 J 0.11 J W k x x x x W = - + - = - + - = - + = - 2. Sum the work done by the spring for each segment of path 2: ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 { } ( 29 ( 29 2 2 2 2 1 2 1 4 4 3 2 2 2 2 2 1 2 2 550 N/m 0 0.020 m 0.020 m 0.020 m 0.1 J 0 J 0.11 J W k x x x x W = - + - = - - + - - = - + = - 3. (b) The work done by the spring will stay the same if you increase the mass because the results have no dependence on the mass of the block. Insight: The work done by the spring is negative whenever you displace the block away from x = 0, but it is positive when the displacement vector points towards x = 0. 34.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

Chapter_8_solved_problems_Physics_1301 - Chapter 8 solved...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online