D&D 5E Giant Boulder vs. Immovable Rod

[jasper]

according to my bing search a 10 ft wide boulder would be are 21,875 pds but they depends on what stone it is.

 

[MarkB]

Unless it's going incredibly fast, like, way more than 10ft/second, then they shouldn't need to save if the players actually say "we dodge to the side". If a player ums and ers about it, sure, an easy-ish save might be warranted, but the thing is 15' tall, so you barely even need to duck to avoid it, given it's a sphere, in a roughly square corridor, if you just move to the side, which, assuming the corridor is barely 15' wide and you're in the middle, takes under a second (just try walking 7.5'). If it's a total surprise and coming at level 30+ mph or something then a save might make sense, but 10'/second is 6.8mph.

This is kind of less of a trap and more of a feature.

And that's when they release the acid down the gutters in the sides of the corridor.

 

[TheDelphian]

Does the boulder have to be solid?

Could be a lot lighter and still maintain some integrity.

just a thought to justify the players plan might work whatever the consequences to the rod.

 

[MatthewJHanson]

The widest point would be at 7', which is over the heads of most PCs.

but the thing is 15' tall, so you barely even need to duck to avoid it

The thing about the 7.5 foot gap is that it's also infinitely thin. So would be crushed under the boulder, just between the boulder and the wall, which is not that much better. If you want even six inches of width, that reduces the height to under five feet of height, and if you want a whole foot of width you'll need a height of less than four feet. (I'd maybe be okay with a small creature managing it, especially since the only small creature in the party is the NPC kobold "guide."
I think lying down is more plausible, but still trying to situate yourself in such a way that none of you gets hit by a boulder passing over in the span of six seconds seems tricky enough to me that I think it's worth a roll.
(Here a graph of what it would look like: Desmos | Graphing Calculator

according to my bing search a 10 ft wide boulder would be are 21,875 pds but they depends on what stone it is.

So my math is that volume of a sphere is 4/3 pi r^3 = 4/3/ pi 7.5^2 = 1767.15. I googled what a cubic foot of granite weighted and got 168 about pounds. 168 x 1767.15 =298,856.

Does the boulder have to be solid?

It doesn't have to be, but I think it makes the most sense to be. (Though maybe there's something else fun inside.)

 

[Imaculata]

Rule of cool: the rod simply stops the boulder, regardless of weight, but make a check to see if it breaks.

 

[Eyes of Nine]

With that in mind what would you do?

Have one of the PCs make an INT check to figure out exactly what you did.

 

[Bawylie]

The concrete ball is hollow like a chocolate bunny.

That’s the only way this trap can get reset anyway.

 

[Eltab]

The concrete ball is hollow like a chocolate bunny.

That’s the only way this trap can get reset anyway.

The hollow rock is full of a magnetic liquid. Wile E. Coyote and an ACME Giant Magnet can drag the rock back up the slope. (Be careful about getting out after setting the hidden panel - especially if he is still carrying the magnet.)

 

[JiffyPopTart]

Real world story. I work in a warehouse. A "heavy" skid for me is 1500 or so pounds. I can move this around fairly easily with a pallet jack by hand, but it takes a little bit to get it moving. The wheels of the pallet jack aren't incredibly large and are coated in rubber.

If you somehow run over the SMALLEST THING (like, not exaggerating, a penny or computer screw) while moving that pallet jack the entire thing is IMMOBILIZED. No amount of brute force will get that 1500 pounds of servers up and over that penny. Its so ridiculous, but its true.

Unrelated to pennies and pallet jacks....if, as a player, I identified a trap and made a reasonable plan to avoid it killing me, I would expect the GM to render it safe or at least tell me that its not a guarantee that its safe before I trigger the trap. If the GM did a GOTCHA and ended up killing my PC off when the trap wasn't neutralized, then one of two things is going to result.

1. I don't want to play in that GMs game anymore.

2. If I do play in that GMs game I will check out of any scene involving traps. My character will go a different way (or even stay behind) rather than me interacting with the trap.

 

[Umbran]

Joking aside, the more you scale up the rock the more clearance there is to avoid it, unless you make the tunnel circular in cross section simply standing aside would avoid such a huge rock.

Or, you make the rock a cylinder...