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Physics/Ladder Fall



I have a puzzle for you.

I work at a store which used to be a bank. For some reason unknown to us, the bank had built a room (we call it the loft) that is suspended from the ceiling. The owner of the store has decided that she wants to store stock in that room. She has provided a ladder of the sort that window washers used to reach a second story window. This ladder does not lock, and is not a two sided ladder, it simply leans against a wall. The floor below is made of tile which is mopped pretty frequently. There is no way for a staff member to avoid putting the ladder on the tile. The loft is two storied up, and so the ladder must be able to reach up that high, about 24 feet.

Today a co worker and I were bringing down items from the loft. She climbed the ladder and went inside the loft to hand me down the items. I was half way up the ladder, and would be passed the items, descend the ladder to the floor level, then go back up again. After completing this task I descended the ladder with no problem at all. While no one bothers to steady the ladder for me half way up, being tired at the end of the day, I neglected to steady the ladder for my co worker. She weighs between 110-102 pounds. When she descended the ladder it gave way from underneath her causing her to fall and hurt her wrist. Luckily enough she wasn't injured beyond that.

My questions are:

1) If I had been there to steady the ladder could I have helped? Or would I have also fallen? I weigh 135 pounds, but I am not physically strong in my arms.

2) Why was the ladder not a problem for me, but it was for my co worker who was up higher?

3) Could the slick tile have anything to do with the ladder falling faster and with more force? This being the case, would it have been possible for me to stop the fall if I had been underneath it, holding it in place? Would that have worked to save the fall?

Thank you for any info!


I hope your friend is OK.  Well, this is pretty simple, but I want to preface that this sounds like one of two problems I can't answer on a forum like this:
1)  A legal problem, because you can't take legal advice from this'll never stand up in court in such an informal matter what the expert credentials.
2)  A homework problem on torque, so if you're in chapter 11 of most main college physics texts (this would be a little simplistic) then I won't solve any full homework problems for you.

First, if you were standing on the ladder and helping dominate the dynamics with your weight on it, or if you were providing any force at all (at the end of a long ladder, it doesn't take much... imagine a wrench that long) then probably would've helped.  A classic problem in physics courses asks how far up a ladder a person can climb before the ladder slips.  The full solution needs coefficients of friction, masses and lengths and angles to solve.  It would've helped if you'd put the ladder at an angle closer to straight-up-and-down or given it any attachment at the top (long slipknot works).  You standing on the ladder closer to the bottom would've applied more vertical force to the floor and therefore more friction and resistance to slipping.  Any force you provided if you were standing on the floor would've been as if it was at the end of a wrench the length of the not strong doesn't matter.  So for question 1...yes, probably wouldn't have happened if it had been being used and suddenly slipped without you there when that was the change.

2)  Yes, classic problem in physics.  Torque in the slipping direction increases as you go up, but remains the same in the counter-rotating direction (barring any massive increase in friction on what you leaned it against).

3)The slick tile has everything to do with the ladder falling, period, but once it slips it doesn't have as much.  It still has an impact on the acceleration if the floor was actually that wet and slick vs if there was some frictional drag on the bottom of the ladder...sure.  Different question entirely than if you'd have been able to help...if you kept it from it's slipping point by applying any force it just wouldn't have slipped.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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