申論題

5. (10%) The ambient temperature in an outdoor ice-skating rink is at -5℃. How much force should one exert to skate smoothly at this temperature if the width and length of the skate blade are 1 min and 30 cm ? Assume that enthalpy of fusion for water is 333.55 J/g. The density of water and ice at this temperature are assumed 1000 kg/m³and 917.5 kg/m³. Please state clearly all of your assumptions.