A suppose you perform a controlled strain measurement

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Unformatted text preview: controlled strain measurement on this material (i.e., systematically increase strain, measure resulting stress). If the material displays linearly elastic behavior between a stain of 0 and 70%, and at a strain of 55% you measure a stress of 40 MPa (40 x 106 N/m2), what is the Young’s modulus of the material? (10) B. Now suppose you cut a strip of the material that is 100 cm in length and has a crosssectional area of 1 cm2, and you hang a 100 kg weight from it. Using your answer in A, calculate the length of the material after you hang the weight. (10) C. Now consider a completely different material, and suppose you conduct a creep test in which you apply an instantaneous, constant stress (step stress) and measure the resulting strain of the material. Sketch the strain response as a function of time for a (1) purely viscous material, (2) purely elastic material, and (3) a Voigt-model viscoelastic material (spring and dashpot in parallel). In all cases, indicate the time at which the step stress was applied, e.g. with an arrow. (10) a) = b) 40 = = 72.7 = 100 × 9.8 = 9.8 × 10 1 1 × 100 9.8 × 10 ∆ ∆ == = 0.135 = = 72.7 × 10 100 ∆ = 13.5 = + ∆ = 100 + 13.5 = 113.5 c) = × 0.55 NAME: NAME: SID: ε Viscous t ε Elastic t ε Voight t NAME: NAME: SID: SID: 4. Consider the following circuit: A. Suppose V = 1.000 V, R1 = 1.000 kOhm, R2 = 2.000 kOhm, R3 = 3.000 kOhm, and R(T) is a thermistor that obeys the following equation: R (kOhm) = exp[100.0*(1/T – 1/300.0)] where T is temperature in Kelvin. Derive an equation that describes the total current in in the circuit as a function of temperature. (15) the B. Using your answer in A, how much of a current change (in A) would be associated with wer an increase in body temperature from 37 C to 39 C? In order to avoid significant rounding errors, carry 4 significant figures throughout your calculation. (10) errors, NAME: NAME: SID: NAME: NAME: SID: 5. Suppose you are interested in measuring the concentration of a solution of the protein lysozyme by spectrophotometry. If the intensity of...
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This document was uploaded on 03/08/2014 for the course BIOE 10 at University of California, Berkeley.

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