You are in the frozen food section of the grocery store and you notice that your hand gets cold when you place it on the glass windows of the display cases. Your friend says this is because coolness is transferred from the display case to your hand. What do you think?

I think my friend got it all wrong, as coolness can not be transferred but heat was actually transferred between my hand and the glass windows

Explanation:

In thermodynamics, coolness can not be transferred, only heat can be transferred

Here is how the mechanism of why i felt cold works, my body gave out heat, hence there was heat transfer from a region of high to a low heat region, equilibrium was reached and I started feeling the coolness in my hands.

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.

3. dark matter

empty space could also be a simple vacuum