In Physics 11, we underwent a design lab project, where we had to design a way to find the initial velocity of a nerf gun (the velocity of the bullet when it has been just fired). We then had to explain our procedure and make our conclusions about our results.
At first, we thought this lab would be successful, but we had one fatal flaw, our final velocity (the velocity of the bullet as it is about to hit the ground) was not 0m/s like we thought it was. As such, it through our entire lab for a loop and we had to start back at square one, and thankfully the first lab was just a practice version.