Explain the following:
In winter, water tank (or ocean) starts freezing from the surface and not the bottom.

Explain the following: Water pipes in colder countries often burst in winter.

Explain the following: (a) The surrounding become pleasantly warm when water in a lake starts freezing in cold countries. (b) The heat supplied to a substance during its change of state, does not cause any rise in its temperature.

Explain the following: The tyre of an automobile is inflated to a lesser pressure in summer than in winter.

The diagram below shows a point source P inside a water container. Four rays A, B, C, D starting from the source P are shown up to the water surface. Show in the diagram the path of these rays after striking the water surface. The critical angle for water air surface is 48^(@) .

Why do lakes freeze from top towards bottom ?

The capacity of a water tank is three times the capacity of another water tank. If 450 L of water is taken out from the first tank and 50 L from the second tank, then the remaining water in the two tanks is equal. Find the capacity of both the tanks.

A small bulb (assumed to be a point source) is placed at the bottom of a tank containing water to a depth of 80 cm . Find out the area of the surface of water through which light from the bulb can emerge. Take the value of refractive index of water to be 4//3 .

A small bulb (assumed to be a point source) is placed at the bottom of a tank containing water to a depth of 80 cm . Find out the area of the surface of water through which light from the bulb can emerge. Take the value of refractive index of water to be 4//3 .

A drain at the bottom of a cylondrical water tank is opened and the height of the water is measured at regular time intervals. The tank is refilled and the process is then repeated. The scatterplot above shows the measured height on the y-axis and time on the x-axis for the trials. Which of the following conclusions can be drawn from the observations in the scatterplot?