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assume T = 20°C and vsound = 343 m/s in air.Calculate the
Chapter 13, Problem 7P(choose chapter or problem)
[Unless stated otherwise, assume \(T=20^\circ \mathrm C\) and \(v_{\mathrm{sound}}=343~\mathrm {m/s}\) in air.]
Calculate the percent error made over one mile of distance by the “5-second rule” for estimating the distance from a lightning strike if the temperature is (a) \(30^\circ \mathrm C\), and (b) \(10^\circ \mathrm C\).
Questions & Answers
QUESTION:
[Unless stated otherwise, assume \(T=20^\circ \mathrm C\) and \(v_{\mathrm{sound}}=343~\mathrm {m/s}\) in air.]
Calculate the percent error made over one mile of distance by the “5-second rule” for estimating the distance from a lightning strike if the temperature is (a) \(30^\circ \mathrm C\), and (b) \(10^\circ \mathrm C\).
ANSWER:Solution: Step 1: PSI is defined as the one pound-force applied to one square inch of area. Again one pound-force is defined as the gravitational force exerted by one pound of mass. At first we will convert pound-force to Newton. 35.0 pound-force is given by 2 f = 35 lbf = (35 lb) × g = (35)(0.45 kg)g = (15.75 kg)(9.8 m/s ) = 154.35 N