Parting Shots

You’re never too young to start designing and engineering structures. John Gruber, P.E. of Sheppard Engineering submitted this photo of his son Alex’s wood tower for his high school physics class. The project, which called for students to construct a tower of balsa wood (G=0.15), limited the tower’s height to 50 cm, with a maximum 8 cm diameter above 15 cm, and required the base to span a 20 cm opening with any orientation. The tower was loaded vertically from the top with both a hanging weight and weights applied to the top. While the tower only weighed 66.7 g (2.35 oz), it certainly stood up to the challenge, resisting 160 lb of applied load without failing—1,089 times its weight!