There's a way to use physics to calculate the digits of $\pi$. I quote from http://math.stackexchange.com/questions/138289/intuitive-reasoning-behind-pis-appearance-in-bouncing-balls

Let the mass of two balls be $M$ and $m$ respectively. Assume that $M=16\times100^nm$. Now, we will roll the ball with mass $M$ towards the lighter ball which is near a wall. How many times do the balls touch each other before the larger ball changes direction? (The large ball hits the small ball which bounces off the wall)

The solution is the first $n+1$ digits of $\pi$.

There's a way to use physics to calculate the digits of $\pi$. I quote from https://math.stackexchange.com/questions/138289/intuitive-reasoning-behind-pis-appearance-in-bouncing-balls

Let the mass of two balls be $M$ and $m$ respectively. Assume that $M=16\times100^nm$. Now, we will roll the ball with mass $M$ towards the lighter ball which is near a wall. How many times do the balls touch each other before the larger ball changes direction? (The large ball hits the small ball which bounces off the wall)

The solution is the first $n+1$ digits of $\pi$.