You are boiling pasta and absentmindedly grab a copper stirring spoon rather than your wooden spoon. The copper spoon has a 20 mm × 1.5 mm r

Question

You are boiling pasta and absentmindedly grab a copper stirring spoon rather than your wooden spoon. The copper spoon has a 20 mm × 1.5 mm rectangular cross section, and the distance from the boiling water to your 35∘C hand is 18 cm. How long does it take the spoon to transfer 40 J of energy to your hand?

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Sigridomena 5 years 2021-07-30T03:15:37+00:00 1 Answers 222 views 0

Answers ( )

  1. Latifah
    0
    2021-07-30T03:17:08+00:00
    Reply

    The spoon to transfer 40 J of energy to your hand is descibed as follows

    Explanation:

    Given  area of cross section of copper spoon is A = 20mm into 1.5 mm

    temperature difference is DT = (100 minus 35) = 65 0C

    length of the spoon is l = 18 cm,

    amount of heat should be transfer Q = 40 J

    coefficient of thermal conductivity of copper k = 400 W by mk

    we know that the thermal conductivity is Q by t = k into A into DT by l

    t = Q into l by k into A into DT

    t = (40 into 0.18) by  \left(400 \times 30 \times 10^{-6} \times 65\right)

    t = 9.23 s

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