# Wonder of the Day: What Causes a Domino to Fall?

Dominoes are a fun toy for kids to play with, but adults can also use them for more elaborate games and even art projects. Some people like to line up dominoes in straight and curved rows and then knock them down one at a time. Others are creative enough to build intricate structures that seem to defy gravity. Today’s Wonder of the Day is inspired by reader Juan, who asks, “What causes a domino to fall?”

Lily Hevesh started playing with her grandparents’ classic 28-piece set when she was 9 years old. From then on, dominoes were her favorite toy. She loved setting them up in a straight or curved line, flicking the first domino and then watching them tumble down one by one. Now, she’s a professional domino artist who creates incredible designs for movies, TV shows and events, including an album launch for Katy Perry. Her YouTube channel has more than 2 million subscribers.

Hevesh says that the science behind her amazing creations is relatively simple. The hardest part is getting the dominoes to stand upright before she begins her work. The pieces are arranged on a flat surface, such as a table or sidewalk, and she sets them up so that each has two matching ends with the same value of dots, or pips. Depending on the type of domino, the values may range from six pips to none or blank.

Once Hevesh has a complete layout, she nudges the first domino so that it tips over and falls into the next piece. This tiny nudge is all it takes to release the potential energy stored in the dominoes. Gravity then pulls the domino toward the ground, causing it to crash into the next domino and start the chain reaction. The energy from the falling domino is converted back into kinetic energy as it slides down the row and hits each piece of the previous domino’s chain, causing them to tip over as well.

The chain continues until either one player wins by playing all of their remaining dominoes or the game reaches a point that nobody can continue. To play the draw game, players shuffle their dominoes and then draw for the lead by picking a piece from the pile that has the same value as the highest domino already played. The leader then plays that piece. Then, when a player cannot continue, they pass their turn to the next player.

The word “domino” is believed to have come from the Italian diminutive of the Latin term dominica, which means “little king.” The name may also have been inspired by the black hooded cloak worn by priests over their white surplices. An earlier sense of the word referred to a long hooded cape worn during a carnival or masquerade. The word has been in use for more than 350 years, making it the longest-lasting of all modern words.