If it's set in the UK, it's more likely they'd be confused by what a kilogram is.

alyss said:

If it's set in the UK, it's more likely they'd be confused by what a kilogram is.

Not really, we use Kilos all the time

But steel is heavier than feathers.

evazion said:

But steel is heavier than feathers.

You can literally see in real time that poor guy's brain explode.

Well, to be pedantic, on earth, a kilo of steel weighs (slightly to nearly twice*) more than a kilo of feathers, by virtue of displacing less air than the corresponding volume of feathers, despite both having the same mass.

(Assuming that both weights are measured within the same region on earth, such that the gravitational acceleration experienced by both masses are approximately the same. [any differences being even more negligible than the buoyancy of displaced air])

(*Depending on what kind of feathers they are and how they are compacted, and also the density of air.)

Of course, since they are actually measuring kilogram-force instead of kilograms, both the steel and feathers actually have equal weight (they balance on the scale), that of one kilogram-force. In this case the kilo-force of feathers actually has (slightly to nearly twice) more mass to make up for the buoyancy of displaced air.

Ah dun getuh

@NNescio
But to be fair, for someone THIS lost the simple scale comparison is probably the best way to visually communicate the principle of what they're talking about, even if it is reductive regarding mass vs net weight.