A composite rod consists of a segment of copper ( ) joined end-to-end to a segment of…

PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A composite rod consists of a

10\,\text{cm}

segment of copper (

k_1=400\,\text{W}/\text{m}\cdot\text{K}

) joined end-to-end to a

15\,\text{cm}

segment of brass (

k_2=120\,\text{W}/\text{m}\cdot\text{K}

). Both segments have the same cross-sectional area of

1.5\times10^{-4}\,\text{m}^2

. The copper end is kept in contact with a heater at

150^{\circ}\text{C}

, while the brass end is attached to a

0.30\,\text{kg}

iron block initially at

20^{\circ}\text{C}

. Neglect heat losses to the surroundings and assume temperature gradients in each segment are linear. What is the initial rate at which the block’s temperature rises? (Specific heat of iron:

c=450\,\text{J}/\text{kg}\cdot\text{K}

.) (a)

1.5\times10^{-1}\,\text{K/s}

(b)

9.6\times10^{-3}\,\text{K/s}

(c)

9.6\times10^{-2}\,\text{K/s}

(d)

1.1\times10^{-1}\,\text{K/s}

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