Density / घनत्व
Density is defined as mass per unit volume.
Density अर्थात घनत्व किसी substance के mass per unit volume को कहते हैं।
Density = Mass / Volume
Relative Density / सापेक्ष घनत्व
The source states that relative density is measured by a hydrometer.
Source के अनुसार Relative Density को Hydrometer से measure किया जाता है।
Important Density Applications / घनत्व के महत्वपूर्ण अनुप्रयोग
- Sea water is denser than normal water.
- A ship rises slightly when it moves from river water into sea water because saline water has greater density.
- Iron is denser than water but less dense than mercury; therefore an iron chunk sinks in water but floats in mercury.
- If floating ice melts in water, the water level remains unchanged according to the source.
Surface Tension / पृष्ठ तनाव
Surface tension is the property of a liquid by virtue of which it tends to minimise its free surface area.
Liquid की वह property जिसके कारण वह अपनी free surface area को minimise करने का प्रयास करता है, Surface Tension कहलाती है।
The source gives surface tension as force acting normally per unit length.
T = F/l
Its unit is N/m.
Important Facts About Surface Tension / पृष्ठ तनाव के महत्वपूर्ण तथ्य
- Surface tension decreases as temperature rises.
- It becomes zero at critical temperature.
- Clean water has higher surface tension than soap solution.
- Raindrops tend to be spherical because of surface tension.
- Floating of a needle on water is associated with surface tension.
- The source connects formation of lead shots and dancing of camphor on water with surface tension.
Kerosene and Mosquitoes / केरोसिन एवं मच्छर
The source states that sprinkling kerosene on water reduces its surface tension, causing mosquitoes floating on the surface to sink.
Cohesive Force / ससंजक बल
Attraction between molecules of the same substance is called cohesive force.
Same substance के molecules के बीच attraction को Cohesive Force कहते हैं।
Adhesive Force / आसंजक बल
Attraction between molecules of different substances is called adhesive force.
Different substances के molecules के बीच attraction को Adhesive Force कहा जाता है।
Capillarity / केशिकत्व
The rise or depression of a liquid in a capillary tube is called capillarity.
Capillary tube में liquid का rise या depression Capillarity कहलाता है।
Applications / अनुप्रयोग
- Blotting paper absorbs ink because its pores behave like capillary tubes.
- Oil rises through the wick of a lamp by capillary action.
- Root hairs of plants draw water from soil through capillary action according to the source.
Viscosity / श्यानता
Viscosity is the property of a fluid by virtue of which internal friction acts between its layers during motion.
Fluid की layers के बीच motion के दौरान acting internal friction से related property को Viscosity कहते हैं।
Bernoulli's Theorem / बर्नौली प्रमेय
For an incompressible, non-viscous fluid in streamlined flow, the source states that total energy per unit volume remains constant along its path.
Incompressible और non-viscous fluid के streamlined flow में total energy per unit volume constant रहती है।
Applications Listed / अनुप्रयोग
- Venturimeter
- Atomizer
- Filter pump
- Motion of aeroplane
Quick Revision / त्वरित पुनरावृत्ति
- Density → Mass/Volume
- Relative density → Hydrometer
- Surface tension unit → N/m
- Raindrop spherical shape → Surface tension
- Blotting paper → Capillarity
- Lamp wick → Capillarity
- Internal friction in fluids → Viscosity
- Venturimeter → Bernoulli's theorem