There are set formulae and procedures to calculate the final velocity of falling objects. All of these have been taught in our schools and colleges, as they form the bases of understanding of how objects exist under set conditions.
If, for example, an object is at rest, at a height of 387 feet. Action is then taken to change this state of rest to one of vertical movement downwards; in other terms, if moved from its static position the object will accelerate downwards at an increasing speed.
One of the formulae of which I wrote earlier can accurately calculate the end velocity of an object which weighs 7.7 Kgs., or 17 pounds in Imperial measurements. If that formula is applied to such an object, it can be easily calculated that the velocity reached by this object is 157.37 feet per second.
Next let us examine the manufacture, construction and maintenance of fire extinguishers, in short form of course. Most extinguishers are made of aluminium, which is extruded and forced into the desired shape, and then further formed by heat spinning and necking to allow the release valve and mechanism to be attached. Older models are made of cast iron or steel, with welded joints.
Now just imagine if you are a protester/agitator/student, standing on top of Millbank Tower. You have a standard fire extinguisher in your hands. You look over the edge, and see, some 387 feet below you, a line of policemen who are vainly attempting to stem a flood of ‘protesters’ from inflicting further damage on the offices, and possibly inhabitants of the offices as well. You pick up that fire extinguisher, which of course you should well know holds pressurised contents, and smilingly but firmly throw it over the edge, straight down at the row of policemen beneath.
In any civilised society, I believe the charge should be one of ‘Attempted Unlawful Killing with Malice Aforethought’; or, in short form ‘Attempted Murder!