Physics 5054/41 — May/June 2010

Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme

questions

marks

minutes

Topics Experimental Contexts · Analysis, Conclusions and Evaluation · Use of Techniques, Apparatus and Materials · Observations and Measurements · Planning Experiments and Investigations

Q1Observations and MeasurementsExperimental ContextsAnalysis, Conclusions and EvaluationUse of Techniques, Apparatus and MaterialsFree sample

A student performs an experiment to find a value for the specific latent heat of vaporisation of water.

An electric kettle, half-filled with water, is placed on a top-pan balance, as shown in Fig. 1.1.

Fig. 1.1

The kettle is switched on with the lid open.

When the water is boiling steadily, a stopwatch is started and the reading on the top-pan balance is recorded.

The total mass $M$ of the kettle and water is measured every 60 seconds. The readings are recorded in the table of Fig. 1.2.

Fig. 1.2

time $t / \text{s}$	$M / \text{g}$	$m / \text{g}$
0	1460	0
60	1410	50
120	1359	101
180	1308
240	1258
300	1208
360	1157

(a)

A column for the total loss in mass $m$ of water is also shown in Fig. 1.2.

Complete this column.

(b)

On Fig. 1.3, plot a graph of $m / \text{g}$ on the $y$ -axis against $t / \text{s}$ on the $x$ -axis.

Draw the line of best fit.

Fig. 1.3

(c)

Describe the relationship between $m$ and $t$ .

(d)

Determine the gradient of the graph.

Show your working clearly.

gradient = ______

(e)

The specific latent heat $L$ of vaporisation of water is given by the relationship

L = \frac{2020}{\text{gradient of the graph}}.

Calculate $L$ .

$L$ = ______ $\text{J / g}$

(f)

The mass of the empty kettle is 860 g.

By using your graph, or otherwise, estimate how long it takes from the start of timing for the kettle to boil dry.

time to boil dry = ______

(g)

The student is careful not to touch the kettle during the experiment.

Suggest two reasons why this is sensible.

______
______

(h)

During the experiment, some steam condenses on the lid and water drips back into the kettle.

Explain what effect this has on the value obtained for $L$ .

The rest of this paper

3 more questions

Q2Experimental Contexts · Use of Techniques, Apparatus and Materials · Planning Experiments and Investigations · Analysis, Conclusions and Evaluation9M
Q3Use of Techniques, Apparatus and Materials · Experimental Contexts · Analysis, Conclusions and Evaluation4M
Q4Experimental Contexts4M

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