If calculations show that one kind of metal isn't strong enough, designers usually have to choose another lightweight, strong material. Ensuring a part's strength is a two-part process. First, the aircraft designers do preliminary calculations to determine whether the part they've designed can withstand the load that will be placed upon it. They don't have to absolutely confirm that a part can withstand a certain load - that's up to the stress department. If the part is too strong it is likely too heavy.
Designers have to strike a balance between weight and strength.
With your classmates, brainstorm answers to the following questions. Also discuss the concept of load. Remember that load is not the same as mass. Load is a force that includes mass along with other inputs like acceleration, gravity, and centrifugal forces. Place a single piece of spaghetti between two desks set 15 to 20 centimetres apart.