exam1-thermo-b - Problems(1 pt each You can choose 6 out of...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Problems: (1 pt. each. You can choose 6 out of 7, or lowest score will be dropped if you complete all of them). USE SI UNITS TO EXPRESS YOUR RESULTS 1) To ensure a perfectly tight fit, aluminum bolts used in airplane construction are made thicker than the holes, and they are cooled down with dry ice before introducing them. If the diameter of the hole is 20mm: what is the diameter of the bolt at 20 ° C, if the two diameters are the same when the bolt is cooled down to -78 ° C (the temperature of the dry ice)? α =24 x 10 -6 ° C -1 (We consider that the diameter of the hole does not change with temperature) 2) An air cooled motorcycle engine loses significant amount of heat through thermal radiation according to the Stefan-Boltzmann equation. Assume that the ambient temperature is 27 ° C. Suppose the engine generates 15hp (11kW) of power and, due to several deep surface fins, has a surface area of A=0.50m 2 . A shiny engine has an emissivity e=0.050, whereas an engine that is painted black has emissivity e=0.95. Determine the equilibrium temperatures for the shiny engine and the black engine. (Assume that radiation is the only mode by which heat is dissipated from the engine). Stefan-Boltzmann constant σ = 5.67x10 -8 W/ m 2 K 4 3) Consider a calorimeter with mass m=100g and specific heat 0.21cal/g ° C, containing 1kg of water at 75 ° C. We drop a mass of iron (C=0.113 cal/g ° C) at 180 ° C. Calculate the mass of iron needed to vaporize 10g of water. (C for water = 1 cal/g
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern