Tag Archives: kinetic

a bit of physics…

In the course of cleaning up after storms, I noticed a large number of twig ends lying on the ground. I wondered: How much force could overcome the modulus of elasticity of these twigs? So I re-uploaded the captured video to the Camtasia editor and tried to find some hail where I could follow the trajectory until impact. I found out that the hail covered a path of about 3 m in about 0.03 sec. Which is a speed of 100 m/s, or 359.9 km/h. So I could put the speed and weight of one hailstone 21g (I hid in the freezer as a keepsake) into the formula for calculating kinetic energy. The approximate energy of the hail just before impact was therefore 105J. The kinetic energy of a 9mm bullet ranges from 100-500J. I understood why even the ends of the branches didn’t stand a chance.