4 ms·

I think you are drastically underestimating the density of bulk metal. Trucks, while impressive as an illustration, are not quite dense enough to be practical

• FooHentai 5y ago
  Absolutely, useful just to illustrate the scale we're talking about for a given amount of energy stored as a real-world analog easy to recall. Assuming you used cast iron as weights that has a density of ~7800kg/m³ at regular temperatures, so you're looking at about 10 cubic meters for that 1kWh of potential energy storage using an abundantly available, non-toxic material that will endure.