The mass of ice, m=ρAL=103×10−4×1=10−1kg,
Energy required to melt the ice, =mSΔT+mL,
⇒i2Rt=mSΔT+mL
⇒(1)2×103×t=[(103×1×10−4)×2000×10]+[(103×1×10−4)×330×103]⇒(1)2×103×t=3.53×104⇒t=35.3s
JEE Main 2021 — Physics Thermodynamics
Due to cold weather, a 1m water pipe of cross-sectional area 1cm2 is filled with ice at −10∘C. Resistive heating is used to melt the ice. Current of 0.5A is passed through 4kΩ resistance. Assuming that all the heat produced is used for melting, what is the minimum time required?
(Given latent heat of fusion for water/ice=3.33×105Jkg−1, specific heat of ice =2\times {10}^{3}J{\mathrm{kg}}^{-1}^{\circ}{C}^{-1} and density of ice =103kgm−3)
Held on 1 Sept 2021 · Verified 6 Jul 2026.
3.53s
0.353s
35.3s
70.6s
Sign in to track your attempts and accuracy.
Sign in to keep a private note on this question. Nothing you write is ever public.
10 mole of an ideal gas is undergoing the process shown in the figure. The heat involved in the process from $P_{1}$ to $P_{2}$ is $\alpha$ Joule ($P_{1}=21.7 \mathrm{~Pa}$ and $\left.P_{2}=30 \mathrm{~Pa}, \mathrm{C}_{v}=21 \mathrm{~J} / \mathrm{K}. \mathrm{mol}, R=8.3 \mathrm{~J} / \mathrm{mol}. \mathrm{K}\right)$. The value of $\alpha$ is $\_\_\_\_$. 
Heat is supplied to a diatomic gas at constant pressure. Then the ratio of $\Delta Q : \Delta U : \Delta W$ is _______.
The r.m.s. speed of oxygen molecules at $47^{\circ} \mathrm{C}$ is equal to that of the hydrogen molecules kept at $\_\_\_\_$ ${ }^{\circ} \mathrm{C}$. (Mass of oxygen molecule/mass of hydrogen molecule $=32 / 2$)
Rods $x$ and $y$ of equal dimensions but of different materials are joined as shown in figure. Temperatures of end points $A$ and $F$ are maintained at $100^{\circ} \mathrm{C}$ and $40^{\circ} \mathrm{C}$ respectively. Given the thermal conductivity of $\operatorname{rod} x$ is three times of that of $\operatorname{rod} y$, the temperature at junction points $B$ and $E$ are (close to): 
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Statement I: Change in internal energy of a system containing $n$ mole of ideal gas can be written as $\Delta U = n C_v (T_f - T_i) = \dfrac{nR}{\gamma - 1}(T_f - T_i)$, where $\gamma = \dfrac{C_p}{C_v}$, $T_i =$ initial temperature, $T_f =$ final temperature. Statement II: Relation between degree of freedom $f$ and $\gamma (= C_p/C_v)$ is $\left(\gamma = 1 + \dfrac{2}{f}\right)$ Choose the correct answer from the options given below
Work through every JEE Main Thermodynamics PYQ, year by year.