I'm currently building a dungeon and a pressure plate activates if 50 lbs. or more are applied to the plate. I'm trying to discern if a character could press the plate with a 10 ft. pole and trigger a trap.
The basic 10 ft pole has been a useful dungeon delving tool for decades, but I'm curious as to how much pressure one can create with the pole.
I tried searching the web for stuff about generating pressure, but I couldn't find anything specific to a pole.
It's not really pressure, it's total force. With a typical pole, it's probably not possible at 10' in front of you (you don't have enough leverage) but would be possible a couple feet in front of you -- depending on your weight, that's probably a third to a fourth of your total body weight being supported by that pole.
that is the original purpose forth 10' pole going back into the antiquity of the game. As a DM i am inclined to let players have it if they do not have a rogue. However if they are checking every square foot of the dungeons ... Hello Random encounters
So first you have to consider the material. Is this an iron pole? I'm presuming we're talking about wood. And then what kind of wood? Oak is much harder than pine. I'm presuming pine, which is soft. Then we have to consider the diameter of the pole. Are we talking like a thin stick, or thick like a walking cane. I'm presuming a walking cane.
But it's going to start bending at 10 feet for sure.
My judgement is it would very easily press 50lbs, I would probably rule it safe to press between 100-200lbs before it bends (not compresses). If it were like 2 inches long, it would be able to support several thousand lbs.
But then I would ask--are we talking pressing down from above, or pressing laterally? Because laterally it's impossible to press more than their body weight unless they're braced against something (unless they're moving)
Another thing to think about is if they were charging forward at the plate--then a it would be easy for a 40lb character to reach 50lb of force.
Direction of force application is also something I was considering.
In this particular case the pole would have to be at an angle. The pressure plate is just past the threshold of a door. The characters would be standing in the room that leads to the room with the pressure plate. The door frame is 7 ft. high. The floor with the pressure plate is smooth. So in my mind it doesn't seem like you could get much leverage to press down on the plate.
I'm not too worried about the realism of the pole bending or breaking unless they are using it in an extreme way.
Basically, the problem is that the torque (force * distance) has to be equal on all sides of the center of weight, and the total weight has to be equal to your weight. Thus, if you're extending your pole by 10' and applying 50 lb of force, that's 500 ft-lb of torque. If your character has a weight of 200 lb, this tells us that the weight being held up by your legs is 150 lb, and thus your feet must be extending by (500 / 150) = 3'4" from your center of mass. Which is not normally going to be possible. It also requires more strength than a single ordinary person can reasonably apply, though two people working together, or one very strong person, could do it -- assuming they know what they're doing.
Withdraw the pole so it's only extending by 3-5' and it's practical enough for an average person
In general I would just call this a disarm trap attempt, at normal difficulty (using a pole instead of thieves' tools), and if they fail the roll... they didn't do it right.
In general I would just call this a disarm trap attempt, at normal difficulty (using a pole instead of thieves' tools), and if they fail the roll... they didn't do it right.
Yeah this discussion is very in the weeds for something best solved with a roll like perception or thieves tools.
I'd maybe give advantage to find weight triggered traps specifically because they are so focused on it but I wouldn't spend too much time on this kind of problem.
The title says it all.
I'm currently building a dungeon and a pressure plate activates if 50 lbs. or more are applied to the plate. I'm trying to discern if a character could press the plate with a 10 ft. pole and trigger a trap.
The basic 10 ft pole has been a useful dungeon delving tool for decades, but I'm curious as to how much pressure one can create with the pole.
I tried searching the web for stuff about generating pressure, but I couldn't find anything specific to a pole.
Anyone have any insight?
It's not really pressure, it's total force. With a typical pole, it's probably not possible at 10' in front of you (you don't have enough leverage) but would be possible a couple feet in front of you -- depending on your weight, that's probably a third to a fourth of your total body weight being supported by that pole.
that is the original purpose forth 10' pole going back into the antiquity of the game. As a DM i am inclined to let players have it if they do not have a rogue. However if they are checking every square foot of the dungeons ... Hello Random encounters
oo, a physics question!
So first you have to consider the material. Is this an iron pole? I'm presuming we're talking about wood. And then what kind of wood? Oak is much harder than pine. I'm presuming pine, which is soft. Then we have to consider the diameter of the pole. Are we talking like a thin stick, or thick like a walking cane. I'm presuming a walking cane.
But it's going to start bending at 10 feet for sure.
My judgement is it would very easily press 50lbs, I would probably rule it safe to press between 100-200lbs before it bends (not compresses). If it were like 2 inches long, it would be able to support several thousand lbs.
But then I would ask--are we talking pressing down from above, or pressing laterally? Because laterally it's impossible to press more than their body weight unless they're braced against something (unless they're moving)
Another thing to think about is if they were charging forward at the plate--then a it would be easy for a 40lb character to reach 50lb of force.
Good question though!
Thanks for the thorough reply.
Direction of force application is also something I was considering.
In this particular case the pole would have to be at an angle. The pressure plate is just past the threshold of a door. The characters would be standing in the room that leads to the room with the pressure plate. The door frame is 7 ft. high. The floor with the pressure plate is smooth. So in my mind it doesn't seem like you could get much leverage to press down on the plate.
I'm not too worried about the realism of the pole bending or breaking unless they are using it in an extreme way.
Basically, the problem is that the torque (force * distance) has to be equal on all sides of the center of weight, and the total weight has to be equal to your weight. Thus, if you're extending your pole by 10' and applying 50 lb of force, that's 500 ft-lb of torque. If your character has a weight of 200 lb, this tells us that the weight being held up by your legs is 150 lb, and thus your feet must be extending by (500 / 150) = 3'4" from your center of mass. Which is not normally going to be possible. It also requires more strength than a single ordinary person can reasonably apply, though two people working together, or one very strong person, could do it -- assuming they know what they're doing.
Withdraw the pole so it's only extending by 3-5' and it's practical enough for an average person
In general I would just call this a disarm trap attempt, at normal difficulty (using a pole instead of thieves' tools), and if they fail the roll... they didn't do it right.
Yeah this discussion is very in the weeds for something best solved with a roll like perception or thieves tools.
I'd maybe give advantage to find weight triggered traps specifically because they are so focused on it but I wouldn't spend too much time on this kind of problem.
Thanks for the responses folks.
I'm not truly concerned with the technicalities, but the geek inside me was curious.