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In this paper, we analyze water demand by urban households in Rwanda who currently lack a piped connection into their home. The analysis uses data from a cross-sectional survey. The results show that public taps are the most widely used water source and that the demand for water from this source is more inelastic than that for water from other water sources. Although some households combine different sources of water, the majority in the sample uses only one source. We use the full household income, including the value of the household's time, and obtain results which indicate income elasticities higher than those obtained using monetary income only. The full cost associated with alternative water sources (including the opportunity cost of the time used) is shown to be important for determining the choice of source — something which has been overlooked in most previous studies.

The mechanical behavior of two types of pasta (noodles and bucatini) was studied in a cantilever-loaded-at-the-end experimental setup. One end of each pasta was fixed while the other end was submitted to forces perpendicular to the line determined by the pasta when undeflected. Elastic curves were studied, resulting in values of $E=2.60$GPa and $E=2.26$GPa for the Young’s modulus of bucatini and noodles respectively. The relation coming from small slopes approximation between the free end’s displacement and the load was analyzed, resulting in values of $E=2.33$GPa and $E=2.44$GPa for the Young’s modulus of bucatini and noodles respectively. Mechanical hysteresis was found in the pasta, resulting in a small deformation. The experiment that we propose illustrates elastic properties of materials, and shows students how to perform measurements of Young’s modulus in cantilevers of different geometries. Furthermore, the experiment can be done with low cost materials, so that it is reproducible in basic mechanics laboratories and it is a good first introduction to some basic concepts of elasticity like mechanical hysteresis.