How do I find the minimum angle a board can have without slipping, using the coefficient of static friction?
Q. A board (whose mass is 40 kg and length is 3m) leans against a wall. The wall is frictionless but the coefficient of friction between the board and floor is 0.12. What is the minimum angle that the board can have without slipping (in degress)? What is the magnitude of the force exerted on the floor by the board?
Asked by Lyny - Mon Nov 17 11:54:02 2008 - - 2 Answers - 0 Comments

A. To answer this question, you have to consider both the forces and the torques acting on the board. For reference, let's say the wall is on the right side, so the board is leaning toward the right. Define some variables: L = length of board m = mass of board = coefficient of friction = angle at which slippage occurs Nf = normal force exerted by floar (upwards against board) Nw = normal force exerted by wall (leftwards against board) Ff = force of friction exerted by floor, just before slippage. First, consider the forces. Since the board is not (yet) moving, all the forces should cancel out. In particular, all the horizontal forces must cancel out; and all the vertical forces must cancel out. Horizontal forces: --- 1. normal force… [cont.]
Answered by RickB - Mon Nov 17 13:02:19 2008

Where can I board my dog during the day in New Jersey?
Q. I want to board my small pomeranian for 4 days, during the day only near Jackson, New Jersey. It's for when we're at Six Flags during the day. She's not used to lots of other dogs but can be around 2 or 3 if neccessary. She's not vicious around other dogs, just gets shy and nervous. PS: I'm from Quebec so interviews and initial meetings are not really possible.
Asked by Meghan H - Sun Jun 29 17:31:35 2008 - - 2 Answers - 0 Comments

A.
Answered by Michelle - Sun Jun 29 17:36:19 2008

Any tips on laying plaster board?
Q. I'm fixing plaster board to a stud wall which will then be skimmed with plaster. Any tips on how to position, lay the board. It is square edged board and i'm fixing it with black dry wall screws. My main querie is do i lay the plaster board horizontally or vertically (it is in oblong sections). And do i stagger the edges as in brickwork. Thanks very much.
Asked by smudgeuk9 - Sun Jul 6 14:36:57 2008 - - 12 Answers - 0 Comments

A. I have done this on quite a number of houses and it is a first-class wall, so much nicer than cheap drywall. Short of doing a full-blown plaster-on-lath wall, this solution is a very nice one. We always hung the board the same as doing drywall, primarily with the boards upright, screwed to the studs with drywall screws, but the board we used, which was "blue board" (the paper was treated with some kind of agent that was supposed to aid bonding and gave it the blue color) did have edges relieved for joints. We used the mesh tape on the joints. As to the skim coating, that is a job that requires a high level of skill. I've tried it, on smaller jobs, like, say, one wall or some repairs and I can tell you that it's not for the DIY'er. I… [cont.]
Answered by John W - Sun Jul 6 14:45:19 2008