Delivery has mass!

A series of power cuts the past two nights (3 am and then 1 am) and then the intermittent restoration of power, from a dodgy generator, finally put the nail in the coffin for the smoke alarms.  Despite new batteries (installed in the small hours to prevent the chirping while the power was off), they were not happy and would not shut up.  The little label on that back advised that we should replace in 2016 (why? said KT), so they were a few years past their sell by date.  Anyway, new ones have arrived at lunchtime, they have the same plug and clip onto the old base (from 2006) and are working once more.  

All enthralling stuff I hear you say, what i found interesting was the potential physics implications of delivery having a weight.  Albeit 10g, it was free and I wondered what the impact of movement having a mass of 0.1N.

Musings over….will go back to work now!