Problem
Robin is making a mobile to hang over her baby sister's crib. She purchased four stuffed animals: a teddy bear (20.7 g), a lamb (23.5 g), a little pony (28.1 g) and a bird (18.5 g). She also purchased three small wooden dowels, each 15.3 cm long and of mass 7.29 g, and thread of negligible mass. She wants to hang the bear and the pony from the ends of one dowel and the lamb and the bird from the ends of the second dowel. Then, she wants to suspend the two dowels from the ends of the third dowel and hang the whole assembly from the ceiling.
1. At what point on the third dowel (or center dowel) should the string (coming from the ceiling) be attached? Give your answer relative to the dowel with the teddy bear and the little pony.
2. At what point on the dowel holding the little pony and the teddy bear - relative to the teddy bear - should the center dowel be attached?
3. At what point on the dowel holding the bird and the lamb - relative to the lamb - should the center dowel be attached?