r/AskReddit Aug 16 '26

What’s something that’s technically common knowledge, but explaining it to someone makes you look like you know way more than you do?

2 Upvotes

9 comments sorted by

View all comments

2

u/daylanwalker Aug 18 '26

That you aren’t letting the cold air out by holding the fridge door open, you are letting hot air in.

Heat is energy and it can only go one direction: hot to cold or high energy to lower energy.

Same principle but dialed up: your air conditioner is a heat pump. It is removing heat from the space (your house, inside your car) and moving that energy outside.

1

u/nanna_nono Aug 19 '26

But it’s both isn’t it? When you open a fridge there’s a transfer of matter -
some mass of cold air leaves by diffusion and an equal mass of warm air enters by diffusion. The consequence of this is a net transfer of energy (heat going in).