I've been learning about pressure and fluid dynamics, and I've stumbled onto a problem. Say you have a straw in a cup. The surface area of the water in the cup is much greater than that of the straw.
So, I would expect Atm. Pressure × Large Area (of the cup) gives a much greater force than Atm. Pressure × Small Area (of the straw). In fact, the force is so much larger I would expect a spectacular jet of water, which obviously does not happen.
What am I missing?
EDIT: So I chose a really bad example. Consider any amount of fluid with two openings of different size (facing upwards). Shouldn't the force due to the atmosphere shoot the water out the smaller opening, since the force on the larger opening due to the atmosphere is greater?