feat: add angular velocity RPM conversions

src/DimensionalQuantities.Extensions.Metric.Tests/MetricConversionsTests.cs

@@ -49,6 +49,18 @@ public void CelsiusConvertsToAndFromAbsoluteKelvin()
 			() => Assert.Equal(0, Temperature.FromKelvin(273.15).AsCelsius(), 10));
 	}
 
+	[Theory]
+	[InlineData(0d, 0d)]
+	[InlineData(60d, 2d)]
+	[InlineData(-120d, -4d)]
+	public void RpmConvertsToAndFromRadiansPerSecond(double rpm, double multiplesOfPi)
+	{
+		double radiansPerSecond = multiplesOfPi * Math.PI;
+		Assert.Multiple(
+			() => Assert.Equal(radiansPerSecond, AngularVelocity.FromRpm(rpm).AsRadiansPerSecond(), 10),
+			() => Assert.Equal(rpm, AngularVelocity.FromRadiansPerSecond(radiansPerSecond).ToRpm(), 10));
+	}
+
 	[Fact]
 	public void CatalogueAccessorsConvertFromKnownSiValues()
 	{

src/DimensionalQuantities.Extensions.Metric/AngularVelocityRpmExtensions.cs

@@ -0,0 +1,16 @@
+namespace DimensionalQuantities.Extensions.Metric;
+
+public static class AngularVelocityRpmExtensions
+{
+	private const double RadiansPerRpm = 2 * Math.PI / 60;
+
+	extension(AngularVelocity)
+	{
+		public static AngularVelocity FromRpm(double value) => AngularVelocity.FromSiBaseUnit(value * RadiansPerRpm);
+	}
+
+	extension(AngularVelocity angularVelocity)
+	{
+		public double ToRpm() => angularVelocity.AsSiBaseUnit() / RadiansPerRpm;
+	}
+}