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
Two copper spheres of radii 6 cm and 12 cm respectively are suspended in an evacuated enclosure. Each of them are at a temperature 15°C above the surroundings. The ratio of their rate of loss of heat is.................
- 2:1
- 1:4
- 1:8
- 8:1
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?
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?
A body cools from 62°C to 54°C in 10 minutes and to 48°C in the next 10 minutes. Find the temperature of the surroundings.
The substance which allows heat radiations to pass through is _______.
(A) iron
(B) water vapour
(C) wood
(D) dry air
A spinning wheel A is brought in contact with another wheel B, initially at rest. Because of the friction at contact, the second wheel also starts spinning. Which of the following energies of the wheel B increases?
(a) Kinetic
(b) Total
(c) Mechanical
(d) Internal
In a calorimeter, the heat given by the hot object is assumed to be equal to the heat taken by the cold object. Does it mean that heat of the two objects taken together remains constant?
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?
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
The atmospheric temperature in the cities on sea-coast change very little. Explain
If heat is supplied to a solid, its temperature
(a) must increase
(b) may increase
(c) may remain constant
(d) may decrease
Answer the following question.
Clearly, state the difference between heat and temperature?
In hot summer after a bath, the body’s __________.
Our normal body temperature is ______.
Give reasons for the following:
Hot metal ball of 80° C is dipped into water of 80°C. The ball will not contract.
What is the SI unit of heat?
Which state of matter has particles that vibrate about fixed equilibrium positions?
Which of the following correctly differentiates heat from temperature?
The concept of thermal equilibrium, where heat flows between bodies until they reach the same temperature, is the basis of which law of thermodynamics?
