Unit d - section 2.3 -- external forces
- 1. Mr.Ilko
- 2. Internal Force – is a force that one part of the structure exerts onto another part of the same structure ◦ These are also known as forces that act within a structure ◦ EX. Press the palms of your hands against one another and push
- 3. There are three main forces that act within a structure You can classify them by the direction in which they within the object The three are; ◦ Compression ◦ Tension ◦ Shear
- 4. Is a force that acts to squeeze an object or push parts within an object together. Solid structures usually resist the force of compression due to the strong materials they are made from Structures with parts that must resist compression include the human body, chairs and shelves
- 6. Is a force that acts to stretch and pull apart something It can cause lengthening and possibly snapping of a component Structures that have parts that resist tension include ski lifts, hydro towers and running shoes
- 8. Is a force that acts to push parts that are in contact with each other in opposite directions Structures with parts that must resist shear include doors, airplanes, and scissors
- 10. When different kinds of internal forces act on a structure at the same time they are called complementary forces Bending is an example of this at work, both compression and tension are involved ◦ If the load is too great the beam may break By looking at were breaks occur, engineers can improve a structure