Get perfect answers to your queries about PHYSICS and MATHEMATICS. Watch my videos in YouTube/ diwakarphysics.
theloveforphysics
Before beating the carpet , both dust particles and carpet are at rest. Hence the dust particles have inertia of rest. When carpet is beaten, its comes to motion but due to inertia of rest, dust particles remains at rest and are separated.
theloveforphysics
Camels have broad feet so that they can walk on sand. As the area of their feet is more, the pressure due to their weight on the sand is less. So they can walk easily without sinking their feet on the sand.
Both sound and light energy are released at the same time. In air the speed of light is 300000000 m/s and speed of sound is 340 m/s. Hence the light reaches the observer instantly and sound after some time.
For example, if an electric discharge between the clouds takes place at a distance of 1km from the observer then lightning flash is seen instantly but sound of thunder will be heard after about 3 seconds.
Cold air from the freezing compartment settles down owing to its higher density and keeps the temperature of the contents below it low.
Infrared rays are invisible rays whose wavelength is more than that of red colour.They produce heating effect. As they have long wavelength, they are least scattered by the fog, mist and smog and dust particles. As they effect a specially treated photographic plate due to the heating effect, they are used in thermal photography.
ALTERNATING CURRENT
1. Its value changes continuously.
2. Its polarity changes periodically.
3. It can be transformed by a transformer.
DIRECT CURRENT
1. Its value doesn't change, it has a constant magnitude.
2. Its polarity doesn't change.
3. It can not be transformed by transformer.
In the direct sunlight there are Infrared Rays. Infrared rays have strong heating effect. But in shade there is no direct sunlight with these heating Rays. Only reflected or diffused light is there. So, temperature is lower in shade than in direct sunlight
A spanner is used to turn a nut to open or tighten it.
The rotational effect depends on the perpendicular distance between the force and the point of application of force. When we increase the perpendicular distance then the Moment of force increases keeping the moment same.
Efficiency is the ratio of work output and work input. As work output is always less than work output for the following reasons, the efficiency is less than 1 or 100%.
1. The movable parts of a machines are not weightless.
2. The movable parts are not frictionless.
3. The parts of the machines are not rigid.
4. The strings or belts are not perfectly elastic in nature.
Electromagnet is a temporary magnet made of soft iron. Soft iron is magnetised by the magnetic field of a coil or solenoid.
Soft iron has high magnetic permeability due to which it gets magnetised quickly and it loses magnetic properties easily due to the fact that it has low magnetic retentivity .
A liquid in a vessel is heated due to the process of convection. In convection heat is transferred by the actual movement of heated particles in upward direction. As the liquid is heated from below its density decreases and hence it rises up and cold liquid settles down and heated. This process continues till whole liquid is heated.
For a moment, it seems like that !
But the compressor does work to extract heat from the content and this heat is thrown out from the refrigerator.
If we keep the door open for long time then heat is taken from the room (from front portion)and thrown back to the room. So the temperature of the room remains the same. Hence, the refrigerator will not be able to keep the room cool.