I know you didn't make this example, but this example appears to be really dumb/unclear. They're saying the TOTAL weight of the plank is 200lbs, right? That doesn't mean that the full 200 lbs is on the right side of the fulcrum. There would still be some plank weight to take into account on the left side, but we are only taking into account the 500lb weight. Am I mistaken here?
That’s a really good question @DoomTrooperTV. The simple answer - that’s the way we do it in the airplane. You don’t try to figure out how much of the ‘plane’ is on each side of the balancing point and then add the passengers and fuel. We go off of where the Center of Gravity is located. If you look at the example in question, you’ll see a CG circle showing where all the weight is concentrated. Since we move the entire plank, the entire plank’s center of gravity is shifted to the right, and so does the moment. In the end, we really only care about the offset from the center of the plank. It would be difficult to do the math (what if the plank is 190lb at one end and 10lb at the other? We’re assuming uniformly distributed weight). If the plank’s CG was over the fulcrum, you wouldn’t have the same question, would you? I hope that answered your question, or at least brought up some more 😜. Thanks for the excellent question. All the best.
Very good information! Although the music made me think my phone notification was going off,, had to keep checking it!
Thanks! Glad you liked it.
And that's how you know it's good music ;)
I know you didn't make this example, but this example appears to be really dumb/unclear. They're saying the TOTAL weight of the plank is 200lbs, right? That doesn't mean that the full 200 lbs is on the right side of the fulcrum. There would still be some plank weight to take into account on the left side, but we are only taking into account the 500lb weight. Am I mistaken here?
That’s a really good question @DoomTrooperTV.
The simple answer - that’s the way we do it in the airplane. You don’t try to figure out how much of the ‘plane’ is on each side of the balancing point and then add the passengers and fuel. We go off of where the Center of Gravity is located.
If you look at the example in question, you’ll see a CG circle showing where all the weight is concentrated. Since we move the entire plank, the entire plank’s center of gravity is shifted to the right, and so does the moment. In the end, we really only care about the offset from the center of the plank. It would be difficult to do the math (what if the plank is 190lb at one end and 10lb at the other? We’re assuming uniformly distributed weight).
If the plank’s CG was over the fulcrum, you wouldn’t have the same question, would you?
I hope that answered your question, or at least brought up some more 😜.
Thanks for the excellent question. All the best.
My brain 🧠 potato 🥔