A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to a temperature of $1000°C$ . Which one of these will cool first
A
Plate
B
Sphere
C
Cube
D
None of these
IIT 1972, Medium
Download our app for free and get started
A
Plate
a (a) Rate of cooling $\frac{{\Delta \theta }}{t} = \frac{{A\varepsilon \sigma ({T^4} - T_0^4)}}{{mc}}$
==> $\frac{{\Delta \theta }}{t} \propto A$. Since area of plate is largest so it will cool fastest.
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.*
A black body at a temperature of $1640\,\,K$ has the wavelength corresponding to maximum emission equal to $1.75 \,\,\mu m.$ Assuming the moon to be a perfectly black body, the temperature of the moon, if the wavelength corresponding to maximum emission is $14.35\,\,\mu m$ is.......$K$
Two spheres of the same material have radii $1\; m$ and $4\; m$ and temperatures $4000 \;K$ and $2000 \;K$ respectively. The ratio of the energy radiated per second by the first sphere to that by the second is
If a metallic sphere gets cooled from ${62^o}C$ to ${50^o}C$ in ${40^o}C$and in the next $10\;\min utes$gets cooled to ${42^o}C$, then the temperature of the surroundings is ......... $^oC$
The ends of a metal bas of constant cross-sectional area are maintained at temperatures $T_1$ and $T_2$ which are both higher than the temperature of the surroundings. If the bar is unlagged, which one of the following sketches best represents the variation of temperature with distance along the bar?
Four rods of same material and having the same cross section and length have been joined, as shown. The temperature of junction of four rods will be........ $^oC$
A black body radiates $ 20\,W$ at temperature ${227^o}C$. If temperature of the black body is changed to ${727^o}C$ then its radiating power will be ..... $W$
Many exoplanets have been discovered by the transit method, where in one monitors, a dip in the intensity of the parent star as the exoplanet moves in front of it. The exoplanet has a radius $R$ and the parent star has radius $100 \,R$. If $I_0$ is the intensity observed on earth due to the parent star, then as the exoplanet transits