Do dusters defy physics?

[Lean L]

Computer duster, as you spray, it gets cooler... how is that possible? Shouldn't any release of energy output heat?

Spoiler

Tool 1st one (name).

 

[StrangerGuy]

I don't get the spoilers.

 

[Lean L]

I don't get the spoilers.

Ignore it for now, I actually do want to know the answer to this.

 

[spidey07]

pv=nrt

 

[StrangerGuy]

pv=nrt

Compressed gas expands, becomes cooler than surrounding air and heat is transferred from your skin to this expanded gas when it touches you. That's why you feel cool.

 

[dighn]

Compressed gas expands, becomes cooler than surrounding air and heat is transferred from your skin to this expanded gas. That's why you feel cool.

and also the gas inside is liquid under press. as it boils, energy is absorbed.

 

[TuxDave]

pv=nrt

I always attributed this to a rapid drop in pressure which causes the condensed air (in liquid form) to convert to gas until the pressure builds up again to maintain the liquid form. The boiling of the liquid is an endothermic reaction which therefore causes the can to get cold.

Edit: Dammit Dighn, type slower.

 

[Lean L]

Compressed gas expands, becomes cooler than surrounding air and heat is transferred from your skin to this expanded gas when it touches you. That's why you feel cool.

Okay that makes sense so far, but what about when you shake the can, it seems to get cooler when in fact, you introduced friction within the can.

 

[geno]

compressing gas = hot
decompressing gas = cold

 

[Brainonska511]

I always attributed this to a rapid drop in pressure which causes the condensed air (in liquid form) to convert to gas until the pressure builds up again to maintain the liquid form. The boiling of the liquid is an endothermic reaction which therefore causes the can to get cold.

Edit: Dammit Dighn, type slower.

P1V1 / T1 = P2V2/T2

Volume remains constant, so with a reduction in pressure, temperature decreases.

 

[dfuze]

is it because it's an endorthermic reaction?

 

[krylon]

Phase change is not considered a reaction

 

[spidey07]

is it because it's an endorthermic reaction?

Nope, it's strictly a pressure thing. Think about how an air conditioner works. It cools the air by the coolant expanding. The compresser then compresses it again and repeat.

 

[MrPickins]

Okay that makes sense so far, but what about when you shake the can, it seems to get cooler when in fact, you introduced friction within the can.

The liquid inside the can is cold after you spray it. Then you cause the liquid to make contact with a greater surface area of the can. Of course it's going to feel colder.

 

[SaDiZTiKStyLeZ]

Buy an electric duster if you'd rather it get hot. I haven't paid for a canned air in over 5 years.

 

[StrangerGuy]

Buy an electric duster if you'd rather it get hot. I haven't paid for a canned air in over 5 years.

Those produces static electricity. Electronics don't like static electricity.

 

[dfuze]

Nope, it's strictly a pressure thing. Think about how an air conditioner works. It cools the air by the coolant expanding. The compresser then compresses it again and repeat.

Ah ok, I gotcha.

 

[dighn]

if you haven't, try turning the can upside down and spray it on something (NOT YOUR SKIN ESP IMPORTANT PARTS) and watch it freeze

 

[eldorado99]

if you haven't, try turning the can upside down and spray it on something (NOT YOUR SKIN ESP IMPORTANT PARTS) and watch it freeze

Fuck that hurts. I sprayed my hand a tiny bit once and it killed. Of course that is because it was instant frostbite.

 

[Blintok]

Bernoulli's principle

 

[MJinZ]

Computer duster, as you spray, it gets cooler... how is that possible? Shouldn't any release of energy output heat?

Spoiler

Tool 1st one (name).

Easily, the air is compressed inside the canister and exists as a liquid.

It literally "boils" when it comes out, so what you feel is the cold liquid expanding and become gaseous.

 

[eldorado99]

Bernoulli's principle

Bernard Bernoulli?

 

[spidey07]

Easily, the air is compressed inside the canister and exists as a liquid.

It literally "boils" when it comes out, so what you feel is the cold liquid expanding and become gaseous.

I become gaseous about 30 minutes after I eat. Same effect?

 

[krylon]

I become gaseous about 30 minutes after I eat. Same effect?

Obviously. Everyone knows it's cool to fart. *rimshot*

 

[SaDiZTiKStyLeZ]

i remembur in hi skool iyt wz cool to inhal the compresed aer cz it got u hi fr brif tim. i think it cuzed brin dmg meby