CAIE A-Level Physics A2 14.1.1 Thermal Energy Is Transferred From a Region of Higher Temperature to a

[Maximum number: 4]

(a)

State

[ 1 ]

(i)

what may be deduced from the difference in the temperatures of two objects,

[ 1 ]

(b)

A block of aluminium of mass 670 g is heated at a constant rate of 95 W for 6.0 minutes. The specific heat capacity of aluminium is $910 \mathrm{Jkg}^{-1} \mathrm{~K}^{-1}$ . The initial temperature of the block is $24^{\circ} \mathrm{C}$ .

[ 3 ]

(i)

In practice, there are energy losses to the surroundings. The actual variation with time t of the temperature $\theta$ of the block is shown in Fig. 1.1.

Fig. 1.1

1. Use the information in (i) to draw, on Fig. 1.1, a line to represent the temperature of the block, assuming no energy losses to the surroundings.
2. Using Fig. 1.1, calculate the total energy loss to the surroundings during the heating process.
energy loss = J

[ 3 ]

1. sketch: straight line from (0,24) to (6,80)

2. temperature drop due to energy loss $=(80-64)=16^{\circ} \mathrm{C}$

energy loss $=0.670 \times 910 \times(80-64)=9800\,\mathrm{J}$

or

energy to raise temperature to $64^{\circ} \mathrm{C}=0.670 \times 910 \times(64-24)$ $=24400\,\mathrm{J}$ $\text{loss}=(95 \times 6 \times 60)-24400=9800\,\mathrm{J}$

CAIE A-Level Physics A2 14.1.1 Thermal Energy Is Transferred From a Region of Higher Temperature to a Topic Practice

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