2.3.4 Consequences of thermal energy transfer

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Question 24

A student investigates the transfer of thermal energy from a beaker containing $cm3150\text{ cm}^3$ of hot water. Under identical initial conditions, the experiment is conducted twice: once with an open beaker A (without a lid) and once with a beaker B (fitted with a lid).

The temperature $θ\theta$ is recorded every $s40\text{ s}$ up to $s240\text{ s}$ . The results are shown in Table 1.1.

Table 1.1

$\text{s}$	$θA/∘C\theta_A / ^\circ\text{C}$	$θB/∘C\theta_B / ^\circ\text{C}$
0	85.0	85.0
40	81.5	83.5
80	78.5	82.0
120	76.0	80.8
160	74.0	79.7
200	72.3	78.8
240	71.0	79.0

Write a conclusion stating how using the lid affects the cooling of the water.

[1]

Calculate the average rate of change of temperature $x_A$ of the water in beaker A. Use the values from Table 1.1 and the equation:

x_A = \frac{\theta_0 - \theta_{240}}{T}

where $θ0\theta_0$ is the temperature at $t = 0$ , $θ240\theta_{240}$ is the temperature at $240\text{ s}$ , and $240\text{ s}$ . Include the unit.

[2]

Calculate the average rate of change of temperature $x_B$ of the water in beaker B. Use the values from Table 1.1 and the equation:

x_B = \frac{\theta_0 - \theta_{240}}{T}

where $θ0\theta_0$ is the temperature at $t = 0$ , $θ240\theta_{240}$ is the temperature at $240\text{ s}$ , and $240\text{ s}$ . Include the unit.

[2]

Thermal energy is transferred both from the surface of the water and from the sides of the beaker. A student suggests that more thermal energy is transferred from the surface of the water than from the sides of the beaker.

State whether the results support this suggestion. Justify your statement by reference to your values of $x_A$ and $x_B$ .

[2]

Suggest a change to the apparatus or the procedure to produce a greater difference between $x_A$ and $x_B$ .

[1]

\text{s}

θA/∘C\theta_A / ^\circ\text{C}

θB/∘C\theta_B / ^\circ\text{C}

85.0

81.5

83.5

78.5

82.0

120

76.0

80.8

160

74.0

79.7

200

72.3

78.8

240

71.0

79.0

2.3.4 Consequences of thermal energy transfer

Question 24

Markscheme

2.3.4 Consequences of thermal energy transfer

Question 24

Markscheme

2.3.4 Consequences of thermal energy transfer

Question 24

2.3.4 Consequences of thermal energy transfer Questions

2.3.4 Consequences of thermal energy transfer

Question 24

2.3.4 Consequences of thermal energy transfer Questions