Calculate the time the boy must wait until the surface

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Reference no: EM13639019

A boy places his glass marbles in an oven at 200degreeC. The diameter of the marbles is 15 mm. After a while, he takes them from the oven and places them in room ;nr at 20degreeC to cool. The convection heat transfer coefficient is approximately 14 W/m2degreeC. Calculate the time the boy must wait until the surface temperature of the marbles reaches 35degreeC. The thermal conductivity and heat diffusivity of the glass marble arc 0.78 W/m degree C and 3.4 times 10-3 m2/s, respectively.

Reference no: EM13639019

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