My Leaking Skylight Peculiarity

[Puma24]

Hey all,

I woke up this morning to find my newly installed skylight was leaking water through it; only one drop at a time thankfully.

I placed a glass underneath it to catch the water, of quite a small diameter in comparison to the skylight (about a third the size), and then sat up, looking at the water running down it, when I noticed something weird.

The skylight is shaped like a convex curve (whether spherical or parabolic, I don't know) so the water thus far, travels from the edge, down to the lowest point on the outisde of the light, then drops off. This is where I lined up my glass to catch the water.

However, I kept watching it and found that sometimes the water didn't make it quite the way down to the lowest point, and dropped off prematurely. The weird thing was, was that every time it did this, it still landed in the glass.

So, it appears at the moment, that if the water falls of prematurely, the momentum it has carrying it towards the centre is sufficient to make it travel a distance through the air, equal to the distance that it would have moved on the surface of the skylight.

Is this a sort of physical property of an object moving along a curved surface, that my roof is of perfect dimensions for, or am I just seeing a lot of freaky coincidence.

 

[kuruman]

So, it appears at the moment, that if the water falls of prematurely, the momentum it has carrying it towards the centre is sufficient to make it travel a distance through the air, equal to the distance that it would have moved on the surface of the skylight.

I think that's the correct explanation. At the time of release, the drop has some horizontal momentum that is (mostly) maintained and thus the drop travels some horizontal distance before dropping into the glass. As to why some drops detach themselves and others do not, my guess is that at some point along the path the drops that detach themselves are moving too fast and the cohesive force that keeps them on the glass cannot provide the needed centripetal acceleration. Drops that follow a path that is already wetted will move faster that drops following a drier path.

 

[256bits]

However, I kept watching it and found that sometimes the water didn't make it quite the way down to the lowest point, and dropped off prematurely. The weird thing was, was that every time it did this, it still landed in the glass

Are you saying that the drops still landed in glass and always in the centre of the glass?
At one third the size - diameter I presume - that could be a large enough target to not miss, and not a bulls eye every time.

 

[A.T.]

Is this a sort of physical property of an object moving along a curved surface, that my roof is of perfect dimensions for, ...

They couldn't make it watertight, so at least they optimized the shape to minimize the size of the bucket needed.