It must be useful for something...

[ZombieCake]

Have you ever tried to throw a 20kg frisbee? More to the point, have you ever been hit by a 20kg frisbee coming down!

I guess that if anyone did get clonked by one they would probably have no memory of who they are or any idea where they've been for a few days so could also claim claim alien abduction and get a spot on one of those UFO conspiracy TV shows.

 

[braveduck]

20 kilos of stainless, what's the scrap on that?

Probably less than he paid for it ,unfortunately.

 

[shotlighter]

It'd make a very heavy duty connection plate, for the radials on a shortwave vertical aerial.

 

[Steve Clark]

Canape holder. Dishwasher & Nuclear Explosion safe.

 

[Flotsam]

Probably less than he paid for it ,unfortunately.

Stainless weighs in at about £1 a kilo so it should be worth £20

 

[Chocolate fireguard]

The attachment point for the ribbons at the top of a very large diameter maypole.

 

[mikem]

Failsafe is to sell it to someone less knowledgeable than yourself, for more money!

 

[Roger W]

Could you use it as a descender? Clip onto your harness through one of the holes and thread the rope through enough of the others to be able to control your descent?

 

[Graigwen]

Could you use it as a descender? Clip onto your harness through one of the holes and thread the rope through enough of the others to be able to control your descent?

The mass would certainly help you descend quicker!
.

 

[Chocolate fireguard]

It would be the weight that did it, not the mass.
Now, about that forum pendant job.....

 

[Custards]

Roll it down a big hill and see how much damage it does to whatever it meets at the bottom? Downside is you'd have to get it back up the hill again...

 

[Fjell]

It would be the weight that did it, not the mass.
Now, about that forum pendant job.....

I would tend to think that gravity over a pitch length can be assumed to be constant. It’s def the mass. The heat dissipation from 20kg of steel is at least an order of magnitude better than a descender, and that is the governing factor (rope melting).

 

[Chocolate fireguard]

Certainly g over that distance should be assumed constant, even by a pendant, but I don't see what that has to do with it.
Surely Craigwen was referring to the additional downward force produced by this piece of steel, which is it's weight.
I'm afraid the bit about heat dissipation lost me too.

 

[Fjell]

Certainly g over that distance should be assumed constant, even by a pendant, but I don't see what that has to do with it.
Surely Craigwen was referring to the additional downward force produced by this piece of steel, which is it's weight.
I'm afraid the bit about heat dissipation lost me too.

Descenders are friction devices that need to lose the heat generated. A 100kg mass dropping 100m is 100,000 joules, all of it into the rope and descender. If the descender had a strong cooling system you could in theory descend at very high speed. A 20kg mass is a chunky heat sink that heats up slowly and then loses it even more slowly to air. Your 100kJ would only heat 20kg of steel by about 12deg, nowhere near enough to threaten a nylon rope assuming perfect distribution, which isn’t the case but is an improvement on a few hundred g in the average descender.

All you have to do is lug it about.

I have done 160m on a dry rope with a Stop in 30deg heat. It was velly toasty.

 

[Graigwen]

It would be the weight that did it, not the mass.
Now, about that forum pendant job.....

Weight = mass x g

Without mass there would be no weight.

(I am not a pedant but I am a M.Inst.P.)
.

 

[mikem]

The problem might be sharp edges cutting the rope, rather than melting - then you would be accelerating due to gravity...

 

[Chocolate fireguard]

Weight = mass x g

Without mass there would be no weight.

(I am not a pedant but I am a M.Inst.P.)

Mass is a scalar quantity - it has size (20kg in this case) but there is no direction associated with it.
The property of the mass that will affect the caver's downward progress is the weight, mg as you say, which is a force (about 200N in this case) and is a vector quantity having size and direction.

 

[mikem]

But for any situation that we are considering mass is proportional to weight, so makes no difference

 

[ChrisB]

Now, about that forum pendant job.....

it's weight

Disqualified

 

[Chocolate fireguard]

Disqualified