Surface Area Argument

[CLAWS]

Possibly the most boringest thread I have ever created.

I am trying to explain "Surface area" to one of the folks at work.

Back when I was doing A-level biology, the lecturer drew two circles on the board. Sphere A was small and Sphere B was big. He then asked which one has the most surface area. Majority said Sphere B. But me, remembering the same question at GCSE level, said Sphere A.

He said I was correct and he explained it, but for the life of me I cannot remember the explanation. Can anyone help?

 

[Stolly]

Possibly the most boringest thread I have ever created.

I am trying to explain "Surface area" to one of the folks at work.

Back when I was doing A-level biology, the lecturer drew two circles on the board. Sphere A was small and Sphere B was big. He then asked which one has the most surface area. Majority said Sphere B. But me, remembering the same question at GCSE level, said Sphere A.

He said I was correct and he explained it, but for the life of me I cannot remember the explanation. Can anyone help?

Easy Sphere is is smaller, but closer. Sphere A is much bigger but is miles away.

Remember kids big things close, small things far away.

 

[CLAWS]

Ummmm..... huh?

 

[Lysander]

So it was a trick question?!

Stolly, your post needs some serious punctuation.

Revised:

Easy. Sphere B is smaller, but closer. Sphere A is much bigger but is miles away.

Remember, kids: big things close, small things far away.

 

[Sinque]

It shouldn't have more surface area to my knowledge?

 

[Vanilla]

Like he said ^^^ the bigger one should haave more surface area if you take away what has already been said about distance.....

 

[Meridian]

Do you mean the ratio of surface area-to-volume? Because surface area alone increases with diameter, so a bigger sphere will always have a bigger surface area.

But volume v. area follows the Square-Cube law: double the diameter and you quadruple the area - but the volume goes up eight time. Thus the ratio of area:volume for the larger is half that of the smaller.


M

 

[Grimley]

Doesn't it have something to do with the smaller the object, the greater the surface area in proportion to its size

 

[oddjob62]

Maybe you're thinking surface area to volume ratios

 

[nightwish]

Surface area of a sphere with radius r is
A = 4*pi*r^2

http://en.wikipedia.org/wiki/Sphere

So the larger the sphere, the larger the radius and the greater the surface area. There's no way for a smaller sphere to have a larger surface area than a larger sphere...

Edit: yikes... 7 replies in the time it took to write this!

 

[CLAWS]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

 

[kaiowas]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

Which relates to surface area to volume ratio.

For a given mass of 'stuff' lots of small lumps of it will have greater total surface area than one big lump of it. Although each small lump would individually have less surface area than the one big lump would have.

 

[Sinque]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

Yes, because the collision theory means that more bits of food will increase the surface area therefore the rate of digestion. But a solid sphere would have a bigger surface area as the volume increases.

http://en.wikipedia.org/wiki/Collision_theory

 

[CLAWS]

Maybe you're thinking surface area to volume ratios

Ah now that rings many bells. Quite possible this might be where I am getting mixed up.

Whats the difference here by the way? Bearing in mind I did A-level biology in 1995 and only got a C.

 

[AGD]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

Yeah that's because the ratio of surface area to volume is greater for small spheres so breaking a large one down into small ones increases the total surface area available for enzymes to act on.

 

[Stolly]

So it was a trick question?!

Stolly, your post needs some serious punctuation.

Revised:

Easy. Sphere B is smaller, but closer. Sphere A is much bigger but is miles away.

Remember, kids: big things close, small things far away.

punctuation nazi

 

[Lysander]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

Nah, you're getting confused. If you have a big ball and make it into four little balls you have greater overall surface area, but something being small doesn't give it a larger surface area than something bigger.

punctuation nazi

I wasn't doing it to feel superior, only to help decipher it. It wasn't very clear before.

 

[Blue Cypher]

Hmm interesting.

I remember reading in a biology text book something along the lines of -

"Animals use their teeth to grind food down into smaller particles, increasing the surface area available for digestion"

Yes many smaller particles have a larger total surface area than one large particle.

 

[Energize]

IT'S SURFACE TO VOLUME RATIO.

/thread

 

[Lysander]

Yes many smaller particles have a larger total surface area than one large particle.

Exactly.