diff --git a/learn-physics-examples.cabal b/learn-physics-examples.cabal
--- a/learn-physics-examples.cabal
+++ b/learn-physics-examples.cabal
@@ -1,5 +1,5 @@
 Name:                learn-physics-examples
-Version:             0.5
+Version:             0.5.0.1
 Stability:           Experimental
 Synopsis:            examples for learn-physics
 Description:         Executables that use the learn-physics library.
diff --git a/src/Projectile.hs b/src/Projectile.hs
new file mode 100644
--- /dev/null
+++ b/src/Projectile.hs
@@ -0,0 +1,77 @@
+{-# OPTIONS_GHC -Wall #-}
+
+module Main where
+
+import Graphics.Gnuplot.Simple
+import Physics.Learn
+
+--type StateTuple = (Double,Vec,Vec)
+--type AccelerationFunction = StateTuple -> Vec
+
+--eulerCromerSolution :: Double -> AccelerationFunction
+--                    -> StateTuple -> StateTuple
+--eulerCromerSolution
+
+-- vertical direction is y direction
+earthSurfaceGravity :: OneParticleAccelerationFunction
+earthSurfaceGravity _state = vec 0 (-g) 0
+
+g :: Double
+g = 9.81
+
+projectileTuples :: Double -> Double
+                 -> OneParticleAccelerationFunction
+                 -> [OneParticleSystemState]
+projectileTuples v0 theta af
+    = oneParticleRungeKuttaSolution af 0.01
+      (0, St (cart 0 0 0) (vec vx0 vy0 0))
+      where
+        vx0 = v0 * cos theta
+        vy0 = v0 * sin theta
+
+yCoord :: Position -> Double
+yCoord r = y
+    where
+      (_,y,_) = cartesianCoordinates r
+
+inAir :: [OneParticleSystemState] -> [OneParticleSystemState]
+inAir = takeWhile (\(_,St r _) -> yCoord r >= 0)
+
+initialProjState :: Double -> Double -> OneParticleSystemState
+initialProjState v0 theta
+    = (0, St (cart 0 0 0) (vec vx0 vy0 0))
+      where
+        vx0 = v0 * cos theta
+        vy0 = v0 * sin theta
+
+-- air resistance quadratic in the speed
+surfaceGravityAirResistance :: Double -> Double
+                            -> OneParticleAccelerationFunction
+surfaceGravityAirResistance m b (_t,St _r v)
+    = netForce ^/ m
+      where
+        netForce      = gravity ^+^ airResistance
+        gravity       = vec 0 (-m * g) 0
+        airResistance = ((-b) * magnitude v) *^ v
+
+trajectory :: [OneParticleSystemState] -> [(Double,Double)]
+trajectory sts = [(x,y) | (_,St r _) <- sts, let (x,y,_) = cartesianCoordinates r]
+
+traj :: Double -> [(Double,Double)]
+traj b = trajectory $ inAir
+         $ oneParticleRungeKuttaSolution
+               (surfaceGravityAirResistance 2 b)
+               0.01
+               (initialProjState 30 (pi/6))
+
+main :: IO ()
+main = plotPathsStyle
+       [Title "Trajectories of 2-kg object, initial speed 30 m/s, angle 30 degrees"
+       ,XLabel "Range (m)"
+       ,YLabel "Height (m)"
+       ,PNG "learn-physics-Projectile.png"
+       ] [(defaultStyle {lineSpec = CustomStyle [LineTitle "No air resistance"]}, traj 0)
+         ,(defaultStyle {lineSpec = CustomStyle [LineTitle "Drag 0.01 kg/m"]}, traj 0.01)
+         ,(defaultStyle {lineSpec = CustomStyle [LineTitle "Drag 0.02 kg/m"]}, traj 0.02)
+         ] >> putStrLn "output sent to file learn-physics-Projectile.png"
+