Initial commit

.gitignore

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+.dub
+docs.json
+__dummy.html
+docs/
+/physics
+physics.so
+physics.dylib
+physics.dll
+physics.a
+physics.lib
+physics-test-*
+*.exe
+*.o
+*.obj
+*.lst

dub.json

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+{
+	"authors": [
+		"Jonathan Harker"
+	],
+	"copyright": "Copyright © 2021, Jonathan Harker",
+	"dependencies": {
+		"quantities": "~>0.11.0",
+		"simpleconfig": "~>0.3.0"
+	},
+	"description": "A tiny physics calculator",
+	"license": "AGPL3",
+	"name": "physics"
+}

dub.selections.json

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+{
+	"fileVersion": 1,
+	"versions": {
+		"quantities": "0.11.0",
+		"simpleconfig": "0.3.0"
+	}
+}

source/app.d

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+import std.conv;
+import std.getopt;
+import std.stdio;
+import std.string;
+import quantities.runtime;
+import quantities.si;
+
+// Aaceleration limits (in g):
+const double lossOfConsciousness = 15.0;
+const double internalInjuries = 25.0;
+const double fatal = 40.0;
+const double puree = 100.0;
+
+const Acceleration g = 9.8 * metre / second /second; // about 35.3 km/h/s
+const Mass typicalHuman = 80 * kilogram;
+
+double getVelocity() {
+    string v = "";
+    while (!isNumeric(v)) {
+        write("How fast was The Flash going? Enter a speed, as km/h: ");
+        v = readln().strip();
+    }
+    return to!double(v);
+}
+
+void main(string[] argv) {
+    double velocity = 0;
+    auto args = getopt(argv,
+        "velocity|v", "How fast The Flash was going", &velocity
+    );
+    if (args.helpWanted) {
+        defaultGetoptPrinter("A stupid superhero physics calculator.", args.options);
+        return;
+    }
+    writeln("Hello, welcome to the stupid superhero physics calculator.");
+    if (!velocity) velocity = getVelocity();
+
+    // v = vᵢ + at; vᵢ = 0, ∴ v = at, a = v/t
+    Speed v = parseSI!Speed(format!"%s km/h"(velocity));
+    Time t = 0.1 * second;
+    Acceleration a = v / t;
+    // F = ma
+    Force f = typicalHuman * a;
+    double accel_g = a / g;
+
+    writefln("The Flash goes from stand-still to %s in a tenth of a second, thus accelerating at %.1f g.", "%.0f km/h".siFormat(v), accel_g);
+    writefln("This would exert a force of %s on a typical human body.", "%.1f kN".siFormat(f));
+
+    if (accel_g > puree) {
+        writefln("Accelerating humans at over %.0f g requires hosing down afterwards.", puree);
+    } else if (accel_g > fatal) {
+            writefln("Accelerating humans at over %.0f g is usually fatal.", fatal);
+    } else if (accel_g > internalInjuries) {
+        writefln("Accelerating humans at over %.0f g results in injuries including internal bleeding.", internalInjuries);
+    } else if (accel_g > lossOfConsciousness) {
+        writefln("Accelerating humans at over %.0f g results in loss of consciousness.", lossOfConsciousness);
+    }
+}