A body cools from $80^{\circ}\,C$ to $60^{\circ}\,C$ in $5$ minutes. The temperature of the surrounding is $20^{\circ} C$. The time it takes to cool from $60^{\circ}\,C$ to $40^{\circ}\,C$ is........... $s$
A$500$
B$\frac{25}{3}$
C$450$
D$420$
JEE MAIN 2023, Medium
Download our app for free and get started
A$500$
a Rate of cooling $\alpha$ Temperature difference
$\frac{80-60}{5}=k\{70-20\}$
$\frac{60-40}{t}=k[50-20]$
$\frac{4 t}{20}=\frac{50}{30}$
$t=\frac{25}{3} min =500\,sec$
$\Rightarrow t=500 \text { seconds }$
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Star $A$ has radius $ r$ surface temperature $T$ while star $B$ has radius $4r$ and surface temperature $T/2$ . The ratio of the power of two starts, $P_A : P_B$ is
Two spherical stars $A$ and $B$ emit blackbody radiation. The radius of $A$ is $400$ times that of $B$ and $A$ emits $10^4$ times the power emitted from $B$. The ratio $\left(\lambda_A / \lambda_B\right)$ of their wavelengths $\lambda_A$ and $\lambda_B$ at which the peaks occur in their respective radiation curves is
Certain quantity of water cools from $70^o C$ to $60^o C$ in the first $5$ minutes and to $54^o C$ in the next $5$ minutes. The temperature of the surroundings is ..... $^oC$
A copper rod and a steel rod of equal cross-sections and lengths $(L)$ are joined side by side and connected between two heat baths as shown in the figure
If heat flows through them from $x = 0$ to $x = 2L$ at a steady rate and conductivities of the metals are $K_{cu}$ and $K_{steel}$ $(K_{cu} > K_{steel}),$ then the temperature varies as (convection and radiation are negligible)
The temperature of a body falls from $62^oC\, to\, 50^oC$ in $10$ minutes. If the temperature of the surroundings is $26^oC$, the temperature in next $10$ minutes will become ...... $^oC$
The radiation emitted by a star $A$ is $10,000$ times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 K$ and $2000 K$ respectively, the ratio of the radii of the star $A$ and the sun is
The sun radiates electromagnetic energy at the rate of $3.9 \times 10^{26}\,W$. It's radius is $6.96 \times 10^8\,m$. The intensity of sun light at the solar surface will be (in $W/m^2$)