Ask any group of engineers about their childhood influences and LEGO is probably near the top. The toy is as popular as ever, keeping to its traditional roots while incorporating pop culture. In 2014, the company ventured into new territory with their big screen release, The LEGO Movie. The first spinoff, The LEGO Batman Movie, is now in theaters.
Several videos on the internet test the strength of LEGO bricks in different ways. The simplistic build and tough plastic show impressive resilience. In one test, a single 2x2 brick only gives out when the force reaches 4,240 Newtons, equivalent to about 950 pounds.
Then we define the point at which we expect the brick’s structural integrity to fail, which is the previously mentioned 950 pounds. Last, we define the environment with atmospheric pressure and water density. Using 1 atm as a unit instead of the longer 1.013x10^5 Pa makes the math more concise and readable.
Finally, we use symbolics and calculate how deep the sub can go before the pressures equal 950 pounds of force. The answer is just over one mile below the surface.
Depth calculation using symbolics
LEGO Batman probably won’t need to send his submarine a mile underwater, though. The vehicle would likely breach and collapse long before the pressure is great enough to crush the individual bricks. And If the Batsub can’t withstand those pressures, an evil lair certainly won’t survive.