A body takes $5$ minutes to cool from $90^oC$ to $60^oC$. If the temperature of the surroundings is $20^oC$, the time taken by it to cool from $60^oC$ to $30^oC$ will be ...... $\min.$
Medium
Download our app for free and get started
(c) $\frac{{90 - 60}}{5} = k\left( {\frac{{90 + 60}}{2} - 20} \right)$
==> $6 = k \times 55$
==> $K = \frac{6}{{55}}$
And, $\frac{{60 - 30}}{t} = \frac{6}{{55}}\left( {\frac{{60 + 30}}{2} - 20} \right)$
==> $t = 11 minute$.
Download our appand 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.*
Similar Questions
- 1View SolutionIn which case the thermal conductivity increases from left to right
- 2Assuming the Sun to be a spherical body of radius $R$ at a temperature of $T\ K$, evaluate the total radiant powerd incident of Earth at a distance $r$ from the SunView Solution
Where $r_{0}$ is the radius of the earth and $\sigma$ is Stefan's constant.
- 3The ratio of the diameters of two metallic rods of the same material is $2 : 1$ and their lengths are in the ratio $1 : 4$ . If the temperature difference between their ends are equal, the rate of flow of heat in them will be in the ratioView Solution
- 4View SolutionPick out the statement which is not true
- 5A spherical black body with a radius of $12\ cm$ radiates $450\ watt$ power at $500\ K$. If the radius were halved and the temperature doubled, the power radiated in watt would beView Solution
- 6A solid sphere of radius $R$ and a hollow sphere of inner radius $r$ and outer radius $R$ made of copper are heated to the same temperature and are allowed to cool in the same environment. Then, choose the $CORRECT$ statementView Solution
- 7A metal ball of surface area $200\;c{m^2}$ and temperature ${527^o}C$ is surrounded by a vessel at ${27^o}C$. If the emissivity of the metal is $0.4$ , then the rate of loss of heat from the ball is .......... $joules $ approx. $(\sigma = 5.67 \times {10^{ - 8}}J/{m^2}\; - s - {k^4})$View Solution
- 8When $p$ calories of heat is given to a body, it absorbs $q$ calories; then the absorbtion power of body will beView Solution
- 9A black body at $1227^o C$ emits radiations with maximum intensity at a wavelength of $5000\;\mathring A$ . If the temperature of the body is increased by $1000^o C$, the maximum intensity will be observed at ...... $\mathring A$View Solution
- 10Two cylinders $P$ and $Q$ have the same length and diameter and are made of different materials having thermal conductivities in the ratio $2 : 3$ . These two cylinders are combined to make a cylinder. One end of $P$ is kept at $100°C$ and another end of $Q$ at $0°C$ . The temperature at the interface of $P$ and $Q$ is ...... $^oC$View Solution