Along cylindrical wood log (k = 0.17 w/m∙k and α = 1.28 × 10−7 m2/s) is 10 cm in diameter and is initially at a uniform temperature of 15°c. it is exposed to hot gases at 550°c in a fireplace with a heat transfer coefficient of 13.6 w/m^2∙k on the surface. if the ignition temperature of the wood is 420°c, determine how long it will be before the log ignites.

Which of the following correctly describes the early view of catastrophism?

30 points - when can a theory be modified if a new type of technology allows for new observations that raise new questions? a. immediately, while the questions about the theory are being asked b. after new hypotheses related to the theory are tested in experiments c. only after the new observations disprove all parts of the theory d. while scientists begin to think about how the theory could improve

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.