Equilibrium - Directions

Using the Equilibrium Concept Builder is quite simple. There are three difficulty levels and each difficulty level involves the same task - you are given one or more angled forces and you must add one east-west force and one north-south force to the object in order to establish an equilibrium. Above the grid with the angled forces is a button titled Add a Force. Tapping on this button pops up the Force Pad along the right side of the Concept Builder. You can tap on the Direction button to toggle through the four possible directions of the added force - east, north, west, south, repeat. Once you are satisified with the direction (you can always change it later), you can tap on the force buttons to set the magnitude of the added force. The force is immediately drawn on the diagram as a blue arrow. Its magnitude and direction are shown below the diagram. You have to repeat this process for a second force. One of the forces must be east or west and the other force must be north or south. There will be blue arrows for these two forces on the diagram. As long as you have two forces in these directions, a Check Answers button will be visible. If you wish to edit a force, simply tap on the force field below the diagram; this will pop up the Force Pad and you can alter your force. Once you are finally satisfied with your answer, tap on the Check Answers button. Feedback will be immediate and your Progress Report will be updated. Your goal is to earn "Stars" and to complete one or more difficulty levels. Stars are earned when you show success on a particular question. Once you show success on all the questions at a particular difficulty level, you will earn the Trophy for that level.