A reusable heat pack contains a solid at its melting point. A 75 W heater is switched on for 240 s. The temperature remains constant during this time. Assume all the energy from the heater is transferred to the solid. The specific latent heat of fusion of the solid is 1.20 × 105 J/kg.
Calculate the mass of solid that melts.
Explain why the temperature of the heat pack remains constant while the solid melts.
110 exam-style questions on Edexcel GCSE Physics 14.2 Specific heat capacity and latent heat, covering 14.2.1 Heating, temperature and changes of state, 14.2.2 Specific heat capacity and specific latent heat, 14.2.3 Specific heat capacity calculation, 14.2.4 Specific latent heat calculation, and 14.2.5 Reducing energy transfer through thermal insulation. Each one has a worked solution and a mark scheme showing where the marks go.