Question EXE.2.SL.TZ0.4
| Date | Example questions Example questions | Marks available | [Maximum mark: 6] | Reference code | EXE.2.SL.TZ0.4 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate, Estimate, Explain | Question number | 4 | Adapted from | N/A |
A sealed bottle contains 0.50 kg of water at an initial temperature of 60 °C. The bottle is made of glass of thickness 3.0 mm and thermal conductivity 0.90 W m−1 K−1.
The temperature of the air outside of the bottle is 20 °C. The surface area of the bottle is 4.0 × 10−2 m2. Calculate the initial rate of thermal energy transfer by conduction through the bottle.
[2]
✓
480 «W» ✓
Explain why the rate calculated in part (a) is decreasing.
[2]
The temperature gradient decreases as the water cools down ✓
The rate of energy transfer is proportional to the temperature gradient ✓
Estimate the initial rate of the change of the temperature of the water in the bottle. State your answer in K s−1. The specific heat capacity of water is 4200 J kg−1 K−1.
[2]
✓
«K s−1» ✓