problem07_57

University Physics with Modern Physics with Mastering Physics (11th Edition)

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
7.57: The two design conditions are expressed algebraically as N 10 66 . 3 4 × = + = mg f ky (the condition that the elevator remains at rest when the spring is compressed a distance y ; y will be taken as positive) and 2 2 1 2 2 1 kx fy mgy mv = - + (the condition that the change in energy is the work fy W - = other ). Eliminating y in favor of k by k y N 10 66 . 3 4 × = leads to k k ) N 10 66 . 3 )( N 10 70 . 1 ( ) N 10 66 . 3 ( 2 1 4 4 2 4 × × + × . N) 10 N)(3.66 10 (1.96 J 10 5 . 62 4 4 4 k × × + × = This is actually not hard to solve for m N 919 = k , and the corresponding x is 39.8 m. This is a very weak spring constant, and would require a space below the operating range
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: of the elevator about four floors deep, which is not reasonable. b) At the lowest point, the spring exerts an upward force of magnitude mg f + . Just before the elevator stops, however, the friction force is also directed upward, so the net force is f mg f mg f 2 ) ( =-+ + , and the upward acceleration is 2 2 s m . 17 = m f ....
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern