Drag depends on shape. Water pushes harder against some forms than others. A streamlined shape meets less resistance on the way down through water. A cone sank fastest at every weight because water flows smoothly around its pointed front. A cylinder sank slowest because its flat face forces water to push back harder.

A parachute slows a falling toy because air pushes back on the open plastic. Cut a large circle from a plastic bag, poke six holes around the edge, and tie six equal strings to the holes. Attach a small toy to the loose ends, then toss the parachute from a high spot. The plastic fills with air as it falls. Gravity still pulls the toy down, but the pushing force from the air slows the descent.

The shape of a boat’s bow changes how hard water pushes back as it moves forward. Build three wooden boats of equal size: one with a flat cuboid shape, one with a half-cylinder bow, and one with a V-shaped bow and curved bottom. Place each in a water tank with pumps creating a steady current, load each with a 300-gram weight, and measure the pushing force with a Newton spring balance. The cuboid boat produces 1.2 N of resistance. The half-cylinder drops to 1.05 N. The V-shaped bow has the least at 0.85 N — its shape lets water flow past with the least resistance.

Shape affects how hard air pushes back on a falling object, even when the total surface area stays fixed. Cut four parachutes from plastic bags — a triangle, a square, a rectangle, and a circle — each at 500 square centimeters. Drop them from a second-floor balcony and time each fall. The round parachute catches more of the pushing force from the air and falls the slowest. The triangular one falls fastest.