1. A mass of 70 g is attached at one end of a rod, and a mass of 30 g is attached at the other end. If the length of the rod is  40 cm, then the fulcrum should be placed _______ cm away from the 70 g mass for the rod to balance.   16   12   24   28   Hint Half-n-half Clue   2. If a walking stick with a mass of 300 g can be balanced by placing a mass M of 120 g at a distance L of 40 cm from the fulcrum, then the center of gravity of the stick is _______ cm away from the fulcrum.   40   16   120   4   Half-n-half Clue   3. Three forces in equilibrium acting at a point can be represented in magnitude and direction by the sides of a triangle taken in order.   True   False   4. A pendulum at rest is in _______ equilibrium.   unstable   neutral   stable   Half-n-half Clue   5. The point where all the _______ of an object appears to be concentrated is called its center of gravity.   weight   centrifugal force   centripetal force   density   Half-n-half Clue   6. Consider a thin rectangular plastic sheet. If a small piece of the plastic breaks off at one of the vertices, then the center of gravity of the remaining plastic (with respect to the original center of gravity)   will not move.   cannot be determined.   will move away from the broken vertex.   will move towards the broken vertex.   Half-n-half Clue   7. There are fundamentally _______ kinds of equilibrium.   four   two   three   Half-n-half Clue