PHYSICS

Principle of MOMENTS states that in EQUILIBRIUM the sum of clockwise MOMENT is equal to the sum of anti clockwise MOMENT.

Winters in most places have very low humidity. For that,  the moisture of our body is lost easily and skin becomes dry quickly.

Temperature of any medium or object falls when it loses the heat. After the heavy shower, water absorbs heat from the surrounding air. Water has high specific heat capacity (i.e. the quantity of heat required by unit mass for the unit rise of temperature)  so water absorbs large amount heat from the surrounding without much rise in it's own temperature. Hence, temperature falls.

Water boils at 100°C at normal pressure of 1 arm or 100000 Pascal. Boiling temperature increases  with the increase in pressure above the liquid surface. When we cook food in pressure cooker, the pressure increases due the retention of vapour and hence the boiling temperature increases in the pressure cooker upto 125°C As food is cooked at higher temperature than 100°C , it is cooked faster in the pressure cooker.

Why is Kelvin considered as SI unit of temperature? Answer: From kinetic theory of matter , it is understood that the average kinetic energy of molecule is directly proportional to the  temperature in Kelvin. When the temperature in this scale is zero then the molecular motion ceases irrespective of nature of any substance. This can be taken as the starting temperature . Hence Kelvin scale is taken as an absolute scale and hence SI unit.

Loudness of a sound is the characteristic of a sound which depend on the intensity of  energy it carries. Intensity of a sound is the amount of energy passing through a surface area of one square metre held perpendicular per sec. Intensity depends on square of amplitude of the wave passing. Hence we can say Loudness is directly proportional to the square of Amplitude. If amplitude is doubled, loudness becomes four times. Loudness depends on distance of source from the listener. Loudness depends on resonance also.

" Any body immersed partially or completely in a fluid experiences an upthrust which is equal to the weight of the fluid displaced by the immersed part of the body"