Hello. In this video, we are going to solve the case of a cable, which is subjected to two unequal loads. We will see that the application of the method which we have seen for a cable subjected to two equal loads, is absolutely possible. So, we will study a free-body for each load. We will obtain the internal forces in each segment of cable, and finally, we will obtain the corresponding forces at the supports. So, when I place a second load on the right of the cable, we can note that the shape of the cable changes, then reaches the equilibrium and stabilizes. We have here represented a structural sketch of this cable with a load of 10 Newtons on the left and of 20 Newtons on the right. We first isolate a free-body corresponding to the force on the left, which we immediately draw again. This free-body includes the segment of cable on the right, the segment of cable on the left, and a load of 10 Newtons. In the Cremona diagram, we introduce this load of 10 Newtons, a parallel component to the transitional part of the cable, and a parallel component to the left part of the cable. We can directly read the value of these internal forces, approximately 10 Newtons here, and 15 Newtons. Copying these internal forces on the free-body, we can see that this internal force of 15 Newtons here, pulls on the free-body, it is thus a tensile internal force, thus this part of the cable is in tension and for the right part, this internal forces of 10 Newtons here, also pulls on the free-body, and thus we also have a tensile internal force in the cable. Well, it is not surprising to have a cable in tension, we have here 10 Newtons, and here 15 Newtons. We now take an interest in the free-body on the right, including the load on the right, a part of the intermediate segment of cable, and a part of the segment of cable which goes up towards the support on the right. So, a horizontal part of cable, or almost horizontal, a part of cable which goes up, and a load of 20 Newtons. We copy this load in the Cremona diagram. We are going to use the internal force of 10 Newtons, which we already know, in the transitional part of the cable, the load of 20 Newtons, and finally, to go up towards the start of our polygon of forces, we will have an internal force whose the value is roughly 22 Newtons. We can copy this internal force in the free-body, here 22 Newtons, we can note that it pulls on the free-body, thus this element is in tension, and the last segment of cable is thus subjected to an internal force of 22 Newtons. I am going to do very quickly, obtaining of the forces at the supports, because there is nothing different from what we have seen previously. We obtain a vertical component on the left and a horizontal component on the left traveling again along the internal force of 15 Newtons, in the other direction. The horizontal internal force on the left is equal to 10 Newtons. The vertical internal force on the left is equal to 11 Newtons. And on the right, we travel again along the internal force of 22 Newtons, in the other direction, then, the internal force on the right, we can see that it is equal to the horizontal internal force on the left and has thus a value of 10 Newtons. And finally, the vertical internal force on the right, which necessarily must, but we can see it, have a value of 19 Newtons for the sum to correspond to the applied load of 30 Newtons. We are going to copy these elements. So, we have 11 Newtons here, 10 Newtons horizontal, 19 Newtons vertical, and once again 10 Newtons horizontal. We have seen in this solution that, on the basis of a photograph or respectively of the structural system which has been given, we can easily obtain the internal forces in the segments of cable, as well as the forces at the supports. In the next lecture, we will see how to determine, without necessarily knowing in advance the shape of the cable, the shape or a possible shape for the cable without having necessarily a photo or a model available before.
