Advertisements
Advertisements
प्रश्न
Why do marine animals live deep inside a lake when the surface of the lake freezes?
Advertisements
उत्तर
Water possesses an anomalous behavour. The volume of a given amount of water decreases as it is cooled from room temperature, until its temperature reaches 4 °C. Below 4 °C, the volume increases, and therefore the density decreases.
When the temperature of the surface of lake falls in winter, the water at the surface becomes denser and sinks. As, the temperature reaches below 4 oC , the density of the water at surface becomes less. Thus, it remains at surface and freezes. As, the ice is a bad conductor of heat, it traps the heat present in the lake's water beneath itself. Hence, no further cooling of water takes place once the top layer of the lake is completely covered by ice. Thus the life of the marine animals inside the lake is possible.
APPEARS IN
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]
Does the temperature of a body depend on the frame from which it is observed?
It is said that mercury is used in defining the temperature scale because it expands uniformly with temperature. If the temperature scale is not yet defined, is it logical to say that a substance expands uniformly with temperature?
As the temperature is increased, the time period of a pendulum
A person's skin is more severely burnt when put in contact with 1 g of steam at 100°C than when put in contact with 1 g of water at 100°C. Explain
Should a thermometer bulb have large heat capacity or small heat capacity?
When a hot liquid is mixed with a cold liquid, the temperature of the mixture ____________ .
The mechanical equivalent of heat ____________ .
If heat is supplied to a solid, its temperature
(a) must increase
(b) may increase
(c) may remain constant
(d) may decrease
A steel wire of cross-sectional area 0.5 mm2 is held between two fixed supports. If the wire is just taut at 20°C, determine the tension when the temperature falls to 0°C. Coefficient of linear expansion of steel is 1.2 × 10–5 °C–1 and its Young's modulus is 2.0 × 10–11 Nm–2.
Heat is measured in Celsius or centigrade.
Temperature in the form of energy.
Analogy
Evaporation:: 100°C: Freezing:: ______.
Two identical beakers A and B contain equal volumes of two different liquids at 60°C each and is left to cool down. Liquid in A has a density of 8 × 102 kg/m3 and specific heat of 2000 J kg-1 K-1 while the liquid in B has a density of 103 kg m-3 and specific heat of 4000 J kg-1 K-1. Which of the following best describes their temperature versus time graph schematically? (assume the emissivity of both the beakers to be the same.)
1 calorie is equal to how many joules?
Which of the following correctly differentiates heat from temperature?
