JEE Main 2022 · 26 Jul · Shift 2 · Physics Q41

← JEE Main 2022 · 26 Jul · Shift 2

PhysicsSingle correct+4 / -1Question 41 of 90

An ice cube of dimensions 60 cm × 50 cm × 20 cm is placed in an insulation box of wall thickness 1 cm. The box keeping the ice cube at 0°C of temperature is brought to a room of temperature 40°C. The rate of melting of ice is approximately :

(Latent heat of fusion of ice is $3.4\times10^5$ J kg $^{-1}$ and thermal conducting of insulation wall is 0.05 Wm $^{-1}$ °C $^{-1}$ )

61\times10^{-3}

kg s

^{-1}

61\times10^{-5}

kg s

^{-1}

208 kg s

^{-1}

30\times10^{-5}

kg s

^{-1}

Answer and worked solution

Official answer: B

Area of the box walls $\approx2(60\cdot50+50\cdot20+60\cdot20)$ cm² $=1.04$ m².

Heat flow $\frac{kA\Delta T}d=\frac{0.05\times1.04\times40}{0.01}=208$ W.

Melting rate $\frac{208}{3.4\times10^5}\approx61\times10^{-5}$ kg s $^{-1}$ .

(B)

Topics:Conduction Latent heat and phase change

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JEE Main 2022 · 26 Jul · Shift 2, Physics question 41