42 Comments

  1. 3:01 It's not so simple. The factor combining a pressure with a raise of melting point temperature is -0,000000074 K/Pa. Skater of 90kg on blade of length 45cm and width 1mm produces pressure that raises melting temperature only by 0,14C. That's not enough for melting the ice. The ice is slippery even if you walk with shoes! The key word is "premelting" (thin layer of liquid H2O present on every solid object even if they have a temperature below 0C). Later, this thin layer of H2O under pressure divides into more 3 layers where the middle layer works like a lubricant and causes ice to be slippery.

  2. Sorry but it's not pressure that makes ice skating possible, a well-known fact taught in many undergraduate-level thermodynamics courses. Unlike virtually any other substance, with increasing pressure the melting point of ice does indeed go up. However, the pressure of a blade on ice raises the freezing temperature by less than one degree.

    The real explanation (which also explains the simple fact that ice is slippery even in the absence of high pressure — a hockey puck, for instance) is that ice has a microscopically thin layer of liquid on its surface at temperatures WELL below the freezing point. Surprising that NdGT "dropped the puck" here.

Leave a Reply

© 2024 FYTube Online - FYTube.Com

Partners: Omenirea.Ro , masini in rate