title: Physics forces not affecting dynamic body Scenekit
body: <p>My scene contains;<br>
  A static body at the root of the scene  </p>
  
  <pre><code>_firstNode = [[SCNNode alloc] init];
  _firstNode.position = SCNVector3Make(0, 0, 0);
  _firstNode.geometry = [SCNSphere sphereWithRadius:950];
  _firstNode.geometry.firstMaterial.diffuse.contents = [UIColor greenColor];
  _firstNode.physicsBody = [SCNPhysicsBody staticBody];
   [[scene rootNode] addChildNode:_firstNode];  
  </code></pre>
  
  <p>A dynamic body with it's pivot property at (0,-1000,0) with a <code>SCNAction</code> that permanently rotates it around the static body. </p>
  
  <pre><code>_secondNode = [[SCNNode alloc] init];
  _secondNode.position = SCNVector3Make(0, 0, 0);
  _secondNode.pivot = SCNMatrix4MakeTranslation(0, -1200, 0);
  _SecondNode.physicsBody = [SCNPhysicsBody dynamicBody];
  _secondNode.geometry = [SCNSphere sphereWithRadius:2];
  _secondNode runAction:[SCNAction repeatActionForever:[SCNAction rotateByX:-1 y:0 z:0 duration:10.0]]];
  [[scene rootNode] addChildNode:_secondNode];
  </code></pre>
  
  <p>When I try apply;  </p>
  
  <pre><code>[_secondNode.physicsBody applyTorque:SCNVector4Make(0, 1, 0, 1) impulse:YES];
  </code></pre>
  
  <p>There is no effect on the node as if it was declared as a static body.</p>