How Dangerous is a Penny Dropped From a Skyscraper?

The popular myth claims a penny dropped from the Empire State Building can kill someone below. Tourists have littered observation deck ledges with change believing this could happen.

• A penny weighs about 2.5 grams (half to a quarter the weight of a bullet) • Without air resistance, it would reach over 300 km/h falling from 443 meters • That's approximately half the speed of a typical bullet

Derek teams up with MythBuster Adam Savage to conduct the ultimate test: dropping pennies from a helicopter onto Derek's body to see if they cause injury.

• Pennies sting when they hit but cause no serious injury • The impact feels like a baseball pitcher throwing a penny hard • Derek experiences bruising but confirms pennies are not lethal

Terminal velocity occurs when gravitational force equals air resistance force, causing an object to stop accelerating and fall at constant speed.

• Moon experiment: hammer and feather fall together in near-vacuum • Earth experiment: feather reaches terminal velocity quickly while hammer keeps accelerating • Hammer experiences greater air resistance due to higher speed but its weight dominates

• Terminal velocity depends on weight-to-drag ratio • Objects with same size and shape have same air resistance but different terminal velocities if weights differ • Air density directly affects terminal velocity

• Felix Baumgartner reached 1,300 km/h from 39 km altitude where air is 60 times less dense • Raindrops fall at only 25 km/h terminal velocity • Hail reaches over 200 km/h terminal velocity, about 10 times faster than rain

• Pennies reach terminal velocity after falling only 15 meters • Terminal velocity is at most 80 km/h • Dropping from 15 meters or 3,000 meters produces identical impact speed

Pennies flutter and tumble as they fall, giving them two different terminal velocities—one on their face and one on their edge—causing oscillation between the two speeds.

Adam Savage's custom 19-year-old wind tunnel demonstrates penny oscillation perfectly, showing the penny bouncing up and down as it transitions between its two terminal velocities.

Because pennies reach terminal velocity so quickly and maintain only 80 km/h maximum speed, they lack sufficient kinetic energy to cause fatal injury.

• Ballpoint pens weigh about twice as much as a penny • They have a smaller cross-sectional area than pennies • This increases the weight-to-drag ratio compared to pennies

Drag coefficient determines how smoothly air flows around an object. Spheres have a drag coefficient of 0.5, while modern bullet shapes have coefficients between 0.1 and 0.3.

Adam drops ballpoint pens from a helicopter at a ballistics gel dummy since the danger level is uncertain. Multiple drops are attempted to find optimal impact conditions.

• No pens penetrated the ballistics gel dummy despite numerous attempts • Plastic ballpoint pens still have too much drag relative to their weight • Pens are confirmed not dangerous falling from tall buildings

• World War I introduced fléchettes: nail-like darts with feathers, up to 15 cm long, dropped from planes • US later created Lazy Dogs in Korean and Vietnam wars, heavier kinetic projectiles • These weapons were cheap to produce but caused indiscriminate damage

• Bullets tumble and fall on their side when dropped from height, not pointy-end down • Cylinders naturally find the most stable orientation relative to air resistance • A bullet fired straight up slows down and tumbles on the way back, arriving slower than it left

The lower limit for fracturing a human skull is around 68 Joules of kinetic energy. A penny delivers only 0.2 Joules; a baseball or large hailstone delivers over 80 Joules.

• Nearly 700 Americans die yearly from falling objects: tiles, bricks, tools, rocks, icicles • Falling measuring tape from 50 stories killed a man in 2014 • Objects weighing hundreds of grams at terminal velocity are likely lethal