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Is Heat a Conserved Quantity? - Physics

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प्रश्न

Is heat a conserved quantity?

टीपा लिहा

उत्तर

Yes, heat is a conserved quantity. Suppose two bodies A and B are at different temperatures, wherein A is higher and B is lower. When they are brought in contact, the heat given by A is equal to the heat gained by B. Thus, the heat is conserved in the system.

Here, we have ignored the heat exchanged with the surroundings. If we consider the surroundings, the heat of the system will be conserved.

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पाठ 3: Calorimetry - Short Answers [पृष्ठ ४६]

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एचसी वर्मा Concepts of Physics Vol. 2 [English] Class 11 and 12
पाठ 3 Calorimetry
Short Answers | Q 1 | पृष्ठ ४६

संबंधित प्रश्‍न

The light from the Sun is found to have a maximum intensity near the wavelength of 470 nm. Assuming the surface of the Sun as a black body, the temperature of the Sun is _____________.

[Wien's constant b = 2 .898 x l0- 3mK]


Answer the following:

There were two fixed points in the original Celsius scale as mentioned above which were assigned the number 0 °C and 100 °C respectively. On the absolute scale, one of the fixed points is the triple-point of water, which on the Kelvin absolute scale is assigned the number 273.16 K. What is the other fixed point on this (Kelvin) scale?


Can the bulb of a thermometer be made of an adiabatic wall?


The length of a brass rod is found to be less on a hot summer day than on a cold winter day as measured by the same aluminium scale. Can we conclude that brass shrinks on heating?


A spherical shell is heated. The volume changes according to the equation Vθ = V0 (1 + γθ). Does the volume refer to the volume enclosed by the shell or the volume of the material making up the shell?


A spinning wheel is brought in contact with an identical wheel spinning at identical speed. The wheels slow down under the action of friction. Which of the following energies of the first wheel decreases?

(a) Kinetic
(b) Total
(c) Mechanical
(d) Internal


A body A is placed on a railway platform and an identical body B in a moving train. Which of the following energies of B are greater than those of A, as seen from the ground?
(a) Kinetic
(b) Total
(c) Mechanical
(d) Internal


As the temperature is increased, the time period of a pendulum


When a solid melts or a liquid boils, the temperature does not increase even when heat is supplied. Where does the energy go?


When a hot liquid is mixed with a cold liquid, the temperature of the mixture ____________ .


A resistance thermometer reads R = 20.0 Ω, 27.5 Ω, and 50.0 Ω at the ice point (0°C), the steam point (100°C) and the zinc point (420°C), respectively. Assuming that the resistance varies with temperature as Rθ = R0 (1 + αθ + βθ2), find the values of R0, α and β. Here θ represents the temperature on the Celsius scale.


A railway track (made of iron) is laid in winter when the average temperature is 18°C. The track consists of sections of 12.0 m placed one after the other. How much gap should be left between two such sections, so that there is no compression during summer when the maximum temperature rises to 48°C? Coefficient of linear expansion of iron = 11 × 10–6 °C–1.


The volume of a glass vessel is 1000 cc at 20°C. What volume of mercury should be poured into it at this temperature so that the volume of the remaining space does not change with temperature? Coefficients of cubical expansion of mercury and glass are 1.8 × 10–6 °C–1 and 9.0 × 10–6 °C–1 , respectively.


A steel ball that is initially at a pressure of 1.0 × 10Pa is heated from 20°C to 120°C, keeping its volume constant.
Find the pressure inside the ball. Coefficient of linear expansion of steel = 12 × 10–6 °C–1and bulk modulus of steel = 1.6 × 1011 Nm–2.


Answer the following question.

Clearly, state the difference between heat and temperature?


In hot summer after a bath, the body’s __________.


Two objects are said to be in thermal contact if they can exchange heat energy.


An earthen pitcher loses 1 gm of water per minute due to evaporation. If the water equivalent of the pitcher is 0.5 kg and the pitcher contains 9.5 kg of water, calculate the time required for the water in a pitcher to cool to 28°C from the original temperature of 30°C. Neglect radiation effects. The latent heat of vaporization in this range of temperature is 580 Cal/gm and the specific heat of water is 1 Cal/gm°C.


The temperature of a liquid drops from 365 K to 361 K in 2 min. Find the time during which the temperature of the liquid drops from 344 K to 342 K.

(Take, room temperature = 293 K)


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