For anyone who wants to know.to crack concrete you need about 2500 to 3000newtons of force.assuming that the height of the table is about 71cm the speed at which the chop sticks are hitting the ground is 3.88m/s.so the weight of the pair 644kg.assuming tye volume of these chopsticks is 10cm³. the density of the material tye chopsticks are made up of should be 64.4kg/cm³