Why doesn't a wide tower fall over?

Think about building a tower out of blocks. A thin, tall stack wobbles, and then down it comes with a clatter. A tower with a wide bottom stays right where it is, even when you bump the table.

So why doesn't a wide tower fall over? Let's find out together, one block at a time.

Earth pulls every part of a tower down toward the ground, all the time. That pull is what presses the tower onto the floor. It is also the pull that makes a tower crash when it tips.

Every tower has a balance point, which means the one spot where its weight is the same on every side. A ruler has a balance point too, right in its middle. That is the spot where it rests on a finger without tipping.

A tower stands on its base, which means the bottom part that touches the floor. The base has edges all around it. Those edges mark where the bottom of the tower ends.

While the balance point sits above the base, Earth pulls the tower straight down onto it. The floor pushes back up and holds the tower. So the tower stays standing, still and steady.

When a tower leans, its balance point slides sideways. If the balance point slides past the edge of the base, there is nothing under it anymore. Then Earth's pull turns the tower over that edge, and it falls.

A thin tower has a small base, with its edges close together. A tiny lean slides the balance point past the edge, and the thin tower tumbles. Now picture a tower with a really wide base. What do you think happens to its balance point when that tower leans a little?

Its balance point slides only a little way, and the edge of the wide base is far off. The balance point stays above the base, so Earth's pull keeps pressing the tower onto it. When the push stops, the wide tower rocks back and stands tall again.

Balance point, base. Earth pulls a tower down at its balance point, and a wide base has edges so far apart that, when the tower leans a little, its balance point stays above the base, so the tower keeps standing.

Next time you build, give your tower a wide base, and watch it stand proud and strong.