Update physics_openrowingmonitor.md

docs/physics_openrowingmonitor.md

@@ -210,7 +210,7 @@ From the perspective of Open Rowing Monitor, there only is a stream of *CurrentD
 
 The following picture shows the time between impulses through time:
 <img src="img/physics/flywheelmeasurement.png" alt="Image showing the currentDt measurements of the flywheel through time" width="700">
-<span class="caption">example currentDt Measurements of flywheel</span>
+<span class="caption">example currentDt Measurements of a flywheel</span>
 
 Open Rowing Monitor combines two types of force detection, which work independently: *basic force detection* and *advanced stroke detection*. Both can detect a stroke accuratly, and the combination has proven its use.