Question

if a door or a window is open on a cold winter day, why is it wrong to say 'Don't let the cold in'?

Answer 1

Explanation:

If in physics

So as in winters the outer atmosphere is too cold and inside our house we have some warmness. So the outer temperature is low and inner temperature is high so when the two different temperature collide do the outer temperature gets in and we feel cold.

Answer 2

Because the cold air enters the room and warm air gets in.