Fill a small plastic water bottle 1/3 full with water and screw on the cap
Over a hard surface, like a table or sidewalk, loosely hold the bottle by the top, swing the base of the bottle forward and up, and let go.
Try to get the bottle to turn in the air and land on its base.
If this is easy for you, try a bigger challenge: landing the bottle on its lid!
How It Works
There are two keys to bottle-flipping. One is getting just the right amount of flip on the bottle. (For that, keep practicing!) The other is filling the bottle just 1/3 full. That leaves the water free to slosh around, and it absorbs some of the bottle’s motion energy, slowing its momentum and making the bottle bounce less when it lands. With less forward spin acting on it, the water flows to the lowest part of the bottle, and gravity pulls that mass to the table. It is more stable upright than a full bottle when it lands because a larger portion of its weight is lower.