A Penny
Myth

You can kill someone by dropping a penny off the Empire State Building (or, more generally, kill someone by dropping a small object from a high enough distance).

Terminal Velocity Busts the Dropping a Penny From the Empire State Building Myth

Due to the way terminal velocity caps the maximum speed that something can fall, a small and light object like a penny will never gain enough speed to kill someone regardless from how high it is dropped from.[1][2][3]

Thus the old saying that says “if you drop a penny from the Empire State Building, it can kill someone below” is a myth.

The terminal velocity of a dropping penny can be up to 100 mph with no wind (Myth Busters estimated 64.4 miles per hour for example), but that won’t kill someone, it would just hurt if it hit the right way.

What Happens When You Drop A Penny Off The Empire State Building? DEBUNKED.

What is Terminal Velocity?

It is the effect of drag force acting against gravitational pull. As an objects falls and the speed of the object increases, drag force increases (the force of the liquid or gas the object is moving through pushing back on it increases).

At first the object’s fall accelerates, but eventually drag force and gravity stops the acceleration and the object falls at a constant speed. This constant speed is terminal velocity.

What Impacts the Speed at Which an Object Falls?

The speed an object falls is impacted by a few factors:

  1. Time in the air. It takes time to reach terminal speed, and the amount of time can be impacted by the other factors below.
  2. The wind. The more wind, the slower the fall.
  3. The “projected area ” (horizontal surface area; like a parachute) relative to its mass object falling. In short, a parachute will have a lower terminal velocity than a bullet, because objects with larger projected areas relative to mass create more drag force.
  4. Mass. An object with little mass, like dust, will fall slower because of forces in the air like wind. Gravity has the same effect on all objects, so weight doesn’t matter in that sense. However, currents in the air can overcome the mass of very light objects and keep them in the air. So, in practice, a feather is going to fall slower than an Apple.
  5. How thin the air is. Thin air means less drag force, so terminal velocity decreases at higher altitudes.

FACT: An object moving downward faster than the terminal velocity will actually slow down until it reaches the terminal velocity.



Conclusion

Due to terminal velocity, you can’t kill someone by dropping a small object from up high. You can however kill someone by dropping a large object with a lot of mass, or a pointy object with enough mass, etc due to the way other aspects of physics works. Plus dropping a penny on someone at terminal velocity would hurt, so just avoiding the whole thing is a good idea.


Citations

  1. Terminal Velocity. Wikipedia.org.
  2. Terminal Velocity. Wikipedia.org.
  3. Can you really kill someone by dropping a penny off the Empire State Building? BusinessInsider.com.


Vote Fact or Myth: "A Small Object Like a Penny Dropped From High Enough Can Kill Someone"

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EE on

Well since a penny cant use a phone this is pretty obvious.

Thomas DeMichele on

Well that is going in the record books under silly mistakes. Thank you for the joke and the correction. 😉