A women dropped dropped her iPhone 1,400-feet when taking a picture on a plane. A few days later it was returned to her by a stranger - and the best part is it still works. The iphone is covered by a silicone case as shown in the picture below.
Assume that the phone hit the ground on its backside and travelled a distance of 7 cm (0.07 m) after the impact. What is the stress on the phone during the impact (in matrix form)? Is the deformation of the silicone case elastic or plastic? What would you expect to be the strain during the impact?