Rwefacts? on Instagram: "The post shares a viral video demonstrating a physics-based hack for removing shallow water from a pool or basin by submerging an inverted plastic cup to fill it, then lifting it mouth-down; atmospheric pressure creates a vacuum inside, preventing the water from spilling out until the cup is tilted. This trick exploits Boyle's law and atmospheric pressure (about 101 kPa at sea level), supporting a water column up to roughly 10 meters high, as confirmed by basic hydrostat