Finding area

**Nerin** · 11-08-2009, 12:08

a bag of stones is .85metres in length each side of the bag. The bag is a cube shape.

How do you calculate how much the bag will roughly cover?

Fremen · 11-08-2009, 12:14

You know how to get the area of a square once you know its side length, right?

Once you have that, just multiply by the number of faces on a cube.

Edit: after reading Yakuza's post, maybe I should clarify. I assumed you were trying to find the surface area of the bag.

Yakuza · 11-08-2009, 12:15

The volume of the bag is (.85m)³, or 0.614125 m³.

However, I think you're trying to find out what area that the stones in the bag will cover, and for that we need more information...the average volume of a stone for one thing, or its average height, width and depth (or radius if you want to approximate the stones as spheres).

Once the volume of stones in the bag is known, then you can calculate the number of stones in the bag, and also can deduce how much area it will cover.

**Nerin** · 11-08-2009, 12:36

Woah,thanks for the quick replies. We were just disagreeing in work so we put ourselves in doubt of eachother

We were looking for a very rough way to see what one bag would cover.
We got the volume as .6 and the boss reckons finding the area the customer wants covered(for example 5x5 metres) then dividing it by the .6 bag would do it. I'm not so sure.

Yakuza · 11-08-2009, 13:30

Let me give you an example to clarify:
Assuming that the stones are smallish stones of (say) 2cm in diameter, then in a bag that was .85 * .85 * .85 m you would be able to cover 42 * (.85 *.85) m², or in this case 30.345 m² (or roughly 5m * 6m).

Thinking of the bag as a cube, the area of the bottom face as a layer of cubes that is (0.85 *0.85) m² or 0.7225m². You would have enough pebbles for 42 such layers (85cm / 2cm, rounded down) hence the 30-odd m².

If the stones are bigger or smaller, you would need to adjust your calcs accordingly

Your boss is dividing an area by a volume which will give you the number of layers that you need, but you will still need the average dimensions / volume of a stone to calc the area it will cover; you could have one boulder of .85 * .85 * .85 m which isn't going to cover much

I hope that helps.

11-08-2009, 12:08	#1
Nerin Moderator Join Date: Jul 2007 Location: Savage Wildlands Posts: 12,488 Adverts \| Friends Mod: Boardean Times, The Nocturnal Forum, The Rafters	Finding area a bag of stones is .85metres in length each side of the bag. The bag is a cube shape. How do you calculate how much the bag will roughly cover?

11-08-2009, 12:14	#2
Fremen Registered User Join Date: May 2006 Location: arrakis Posts: 1,147 Adverts \| Friends	You know how to get the area of a square once you know its side length, right? Once you have that, just multiply by the number of faces on a cube. Edit: after reading Yakuza's post, maybe I should clarify. I assumed you were trying to find the surface area of the bag. Last edited by Fremen; 11-08-2009 at 12:25.

11-08-2009, 12:36	#4
Nerin Moderator Join Date: Jul 2007 Location: Savage Wildlands Posts: 12,488 Adverts \| Friends Mod: Boardean Times, The Nocturnal Forum, The Rafters	Woah,thanks for the quick replies. We were just disagreeing in work so we put ourselves in doubt of eachother We were looking for a very rough way to see what one bag would cover. We got the volume as .6 and the boss reckons finding the area the customer wants covered(for example 5x5 metres) then dividing it by the .6 bag would do it. I'm not so sure. __________________ ~ NerinOnline.com ~ Forums ~ Twitter ~ Feedburner ~ Compromise is for people that are wrong. I <3 you and i want to hold your hand ^_^ I DEMAND all of your pokemon cards and jaffa cakes. We need less feminazis, moar femininjas. Blood donations are needed urgently!

11-08-2009, 13:30	#5
Yakuza Registered User Join Date: Nov 1999 Location: Dublin Posts: 634 Adverts \| Friends	Let me give you an example to clarify: Assuming that the stones are smallish stones of (say) 2cm in diameter, then in a bag that was .85 * .85 * .85 m you would be able to cover 42 * (.85 .85) m², or in this case 30.345 m² (or roughly 5m 6m). Thinking of the bag as a cube, the area of the bottom face as a layer of cubes that is (0.85 0.85) m² or 0.7225m². You would have enough pebbles for 42 such layers (85cm / 2cm, rounded down) hence the 30-odd m². If the stones are bigger or smaller, you would need to adjust your calcs accordingly Your boss is dividing an area by a volume which will give you the number of layers that you need, but you will still need the average dimensions / volume of a stone to calc the area it will cover; you could have one boulder of .85 .85 * .85 m which isn't going to cover much I hope that helps. Last edited by Yakuza; 11-08-2009 at 13:35.

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11-08-2009, 12:15	#3
Yakuza Registered User Join Date: Nov 1999 Location: Dublin Posts: 634 Adverts \| Friends	The volume of the bag is (.85m)³, or 0.614125 m³. However, I think you're trying to find out what area that the stones in the bag will cover, and for that we need more information...the average volume of a stone for one thing, or its average height, width and depth (or radius if you want to approximate the stones as spheres). Once the volume of stones in the bag is known, then you can calculate the number of stones in the bag, and also can deduce how much area it will cover.