 Hi, welcome to the third and final unit of sailor.org's Mechanics One course. In units one and two we focus a lot on how forces can make structures move or twist and in this unit we're really going to focus on how forces can make structures bend or break. So when a beam experience is increased forces, it will bend and you probably have the experience of walking up an old flight of stairs and you can hear and you can feel the structure of bending underneath your feet. Now a lot of bending can safely be ignored, sometimes it can be reversed, but sometimes bending leads to breaking. So in this course we're going to look at what is the maximum amount of stress and strain that a structure can take before it fractures. And you've made these kinds of analytical decisions in your everyday life. If you're climbing a tree you might think about what happens if I grab for the next branch? Will it support my weight? Will it bend? Will it break? Or maybe you've been playing with a paper clip, bending it back and forth until it breaks, counting how many times? That's the kind of calculation we're going to do in this unit. Now before I let you get started, a few reminders. First, this will take about 35 hours to complete similar to the other units. Second, there will be again an end of unit assessment, not graded, but grade practice for your final exam. Now third, when you're done with the end of unit assessment, it's time to take your final exam. Just a reminder that that will be the complete grade for this course. 70% is passing and you should budget about an hour and a half to two hours for the final. Now finally, I want to say thank you for joining us in Mechanics One. It's been a pleasure to be your guide, and I hope you've learned a lot. Good luck.