ps8c22 - Ph 111.01 October 24, 2008 PS 8c (22) Problem 1....

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Ph 111.01 October 24, 2008 PS 8c (22) Problem 1. The object shown below (length = 4 m) remains completely stationary, despite the fact that three forces act on it. Forces 1 and 3 act at either end, while force 2 acts 1/4 of the way from the left end. If the size of force 3 is 4 N, then how large must the other two forces be? F 1 = N F 2 = N (For excellent practice, see if you can also get these answers using different pivots!) F 1 L/4 pivot point 2 F 3 =4N F 2 0 L pivot point 1 pivot point 3 Solution. Let's think about pivot point 1. For the torques to vanish, F 2 has to be four times bigger than F 1 . So F 2 = 16 N. (I consider the sign to be given by the arrows.) Then for the total force to be zero, F 1 would have to be equal to 12 N. 1 2 12 N 16 N F F = = "Excellent practice" is hard to pass up. What can we conclude by looking at pivot point 2? That F 1 must be three times bigger than F 3 , since its lever arm is three times smaller. Or, what about pivot point 3? We can conclude that F 1 must be 3/4 of F 2 . But that doesn't give us actual values. We would have to write down two equations: () 123 3 12 4 0 0 FFF FL F L += = and solve for F 1 and F 2 . I'm sure this would give the same results.
Background image of page 1

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

View Full DocumentRight Arrow Icon
Problem 2 = Walker P. 11-14.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/13/2010 for the course PHYSICS 111 taught by Professor Staff during the Fall '08 term at S.F. State.

Page1 / 4

ps8c22 - Ph 111.01 October 24, 2008 PS 8c (22) Problem 1....

This preview shows document pages 1 - 3. Sign up to view the full document.

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