A 150 W heater warms a 1.2 kg steel mould insert. The temperature of the insert rises by 40 ∘C40\ ^\circ\mathrm{C}40 ∘C. The specific heat capacity of the steel is 450 J kg−1 ∘C−1450\ \mathrm{J\,kg^{-1}\,{}^\circ C^{-1}}450 Jkg−1∘C−1. Assume that all of the energy from the heater is transferred to the insert. For how many minutes is the heater switched on? Use E=PtE=PtE=Pt and E=mcΔθE=mc\Delta\thetaE=mcΔθ.
2.0 min2.0\ \mathrm{min}2.0 min
144 min144\ \mathrm{min}144 min
0.040 min0.040\ \mathrm{min}0.040 min
2.4 min2.4\ \mathrm{min}2.4 min
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.