A balloon full of helium has more mass than a balloon without helium, but less weight https://en.m.wikipedia.org/wiki/Mass_versus_weight.
~~Methane weighs more than nitrogen (70% of atmosphere); you lose weight and mass. Molar mass of nitrogen 7; methane 16. ~~
https://discuss.tchncs.de/comment/19776581
Edited to comment about mass: Except that a) methane is leaving the body and is not necessarily being replaced; the volume is simply taken up by a contracting colon and b) methane may be less dense than air, but it does contain fecal particles as well, which are tiny but still heavier than air.
I’m saving this one for later today when I have time, but came here to say - when I visited Toronto I was struck by how bad the streetcars were. The way they’re done is like busses, except they can’t detour because rails, and they block two lanes of traffic at many stops because they run in the middle two lanes. So they’re held up by car traffic and traffic signals, and themselves contribute to car traffic by blocking the road. And they allow parking in the outside lanes. It’s a bad system. They should give the trams dedicated space. Take the cars out, put in a bike lane and give the trams space.
But isn’t this the city that’s ripping out bike lanes