Question

In Session 31: Related Rates , of 18.01 course there's an odd recitation video with a trick question , the one with the ladder , while his method seemed to work it also seemed to completely ignore gravity , anyone else notice that?

Answer 1

In this problem we're looking at the instantaneous rate of change in the height of the end of the ladder at a time when the ladder is being supported by the wall and the bottom is being dragged away from the wall. At the relevant time, the bottom of the ladder is in contact with the ground and another part of the ladder is supported by the wall, so the law of gravity is being obeyed and all is well in the world. Of course the situation changes at the point when the ladder is pulled far enough away to no longer be supported by the wall, but that point is outside the range of what we're considering in this problem.

Answer 2

Explains my head ache , took me a minute to see the problem the way you explained it , but then another 20 considering how to react to the edge of the wall with gravity entering as a factor , and answer the question correctly , for the first few units is it prudent to over think these problems to the end? As gravity is a value we do know unlike something we won't bother with unless asked such as air resistance