Advertisements
Advertisements
Question
Why do marine animals live deep inside a lake when the surface of the lake freezes?
Advertisements
Solution
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
RELATED QUESTIONS
Define emissive power and coefficient of emmision of a body.
A pinhole is made in a hollow sphere of radius 5 cm whose inner wall is at temperature 727oC. Find the power radiated per unit area. [Stefan’s constant σ = 5.7 x 10-8 J/m2 s K4 , emissivity (e) = 0.2]
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]
What is the temperature of the triple-point of water on an absolute scale whose unit interval size is equal to that of the Fahrenheit scale?
The susceptibility of magnesium at 300K is 1.2 x 10-5. At what temperature will the susceptibility increase to 1.8 X 10-5?
The substance which allows heat radiations to pass through is _______.
(A) iron
(B) water vapour
(C) wood
(D) dry air
The kinetic energy per molecule of a gs at temperature T is ________.
(a) `(3/2)RT`
(b) `(3/2)K_BT`
(c) `(2/3) RT`
(d) `(3/2)("RT"/M)`
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?
Is heat a conserved quantity?
As the temperature is increased, the time period of a pendulum
Which of the following pairs of physical quantities may be represented in the same unit?
A concrete slab has a length of 10 m on a winter night when the temperature is 0°C. Find the length of the slab on a summer day when the temperature is 35°C. The coefficient of linear expansion of concrete is 1.0 × 10–5 °C–1.
In hot summer after a bath, the body’s __________.
‘An object contains more heat’- is it a right statement? If not why?
Two tumblers of A and B have water at 50°C temperature. If the water from A and B is poured into tumbler C. The temperature of C is ______.
Which statement about states of matter is most accurate?
What physical quantity does temperature primarily indicate?
