It states that if net torque acting on an isolated system is zero, the angular momentum remains conserved. Since Torque is equal to the rate of change of angular momentum so when torque is zero, dL/dt=0 So,...
Seriously,It's called the tripple point.The temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states.The triple point of pure water is at 0.01°C...