There is a standard impact test that is used in the fenestration industry. An air cannon is used to fire a piece of lumber at the unit being tested. The mass of the 'missile' is 4.09 kg. The velocity of the missile is 15.26 m/s. I am wondering if there is a way to approximate this test without an air cannon by using a free-falling object in a drop tube. I currently have a drop tube that would allow for a 2 meter freefall. I calculated that this should give the missile a velocity of 6.21 m/s in freefall. Can I compensate for this slower velocity by adding mass to the projectile to give an equivalent impact? How much mass would be required at 6.21 m/s to equal the impact of a 4.09 kg projectile at 15.26 m/s? Or is there no way to equate the impacts? Thank you for your help.