1. can an object be moving and still be in equilibrium? 2. consider a ring with a pin in the center that's not connected to the ring. three weights are attached to the ring at different angles and are hanging from the side of the apparatus where the ring lies. what criteria will decide when the forces on the ring are in equilibrium? 3. draw a set of three vectors whose sum is zero 4. how will you estimate the uncertainty of each force acting on the ring? 5. how will you estimate the uncertainty of each angle measurement? 6. how much error will be introduced if the table is not level? how could you test this empirically? 7. what are the units of sine and cosine? does your answer depend on the units of the angle (degrees or radians)?