A student investigates some thermal properties of dry soil and water by conducting two experiments in a laboratory.
The student starts with dry soil in a beaker. Water of volume 100 cm3 is heated and added to the soil.
(i) Calculate the rise in temperature θR1\theta_{\text{R1}}θR1 of the soil, using the equation:
θR1=θM1−θS \theta_{\text{R1}} = \theta_{\text{M1}} - \theta_{\text{S}} θR1=θM1−θS(ii) Calculate the fall in temperature θF1\theta_{\text{F1}}θF1 of the hot water, using the equation:
θF1=θH1−θM1 \theta_{\text{F1}} = \theta_{\text{H1}} - \theta_{\text{M1}} θF1=θH1−θM1(iii) Calculate the ratio S S\,S using the equation:
S=θR1θF1 S = \frac{\theta_{\text{R1}}}{\theta_{\text{F1}}} S=θF1θR1The beaker now contains 100 cm3 of cold water at room temperature. Another volume of 100 cm3 of hot water is heated and added to the cold water.
(i) Calculate the rise in temperature θR2\theta_{\text{R2}}θR2 of the cold water, using the equation:
θR2=θM2−θS \theta_{\text{R2}} = \theta_{\text{M2}} - \theta_{\text{S}} θR2=θM2−θS(ii) Calculate the fall in temperature θF2\theta_{\text{F2}}θF2 of the hot water, using the equation:
θF2=θH2−θM2 \theta_{\text{F2}} = \theta_{\text{H2}} - \theta_{\text{M2}} θF2=θH2−θM2(iii) Calculate the ratio W W\,W using the equation:
W=θR2θF2 W = \frac{\theta_{\text{R2}}}{\theta_{\text{F2}}} W=θF2θR2The student predicts that S S\,S should be equal to 0.9×W0.9 \times W0.9×W. State whether these experimental results support this prediction. Justify your answer by comparing the values with reference to experimental accuracy (where results within 10% of each other are considered to support the prediction).
Suggest two temperatures that it would be sensible to keep constant when carrying out this investigation to ensure a fair comparison.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.