On a cold evening the night before her son's surprise birthday party, Mrs. Kowal blew up 20 balloons. She inflated them in the garage so that her son would not see them. Early in the morning, she brought the inflated balloons into the house to decorate for the birthday party. Within five minutes, half of the balloons had popped. What mistake had she made?

One cold March day, Donna asked her father if she could go for a bike ride. The snow had melted and she was eager to go, as she hadn't ridden her bike since the previous September. Her father replied that she could go, but that he suspected her tires would probably need some extra air. Why might he say this?

The lift force on the airplane wing is given by the distributed load L(x) = 15(1- 0.04x) KN/m, the engine has a weight of 20 KN, and the weight of the wing is given by w(x) = (5-0.5x) KN. Determine the reaction force and moments at the root of the wing.