Who could explain what is zero reference point in conservation of energy?
This is a really good question. Potential energy, any kind, is relative energy. So there has to be a specified reference point to be relative to. Typically, we set all potential energy to zero at that specified reference point. When we do that, it becomes the “zero reference point.” For example, when we toss a stone straight up from a height h above ground, we can set the zero point h = h0 > 0 or we can set it to ground level h = 0. When the stone reaches its max height, we measure that from h = h0 > 0 or from ground level h = 0. Makes no difference as far as the potential energy is concerned, we just need to keep our zero reference point consistent throughout the problem. For example, the stone’s potential energy PE = mg(H – h) + mgh where (H – h) is the height above h and h is the launch height above ground. H, then, is the max height above the ground. Had we set h = 0, ground as the zero reference point, we’d be left with PE = mgH, which is straight forward. Had we instead set h = h
