Questions

A nanosecond (ns) is an SI unit of time equal to one thousand-millionth of a second or one billionth of a second.

• That is, 1/1,000,000,000 of a second, or 10^−9 seconds.

The amount of water vapor in the air is called Humidity. The amount of water vapor that air acn hold depends on the temperature of the air. The amount of water vapor in the air as compared with the amount of water that the air could hold is called Relative humidity.

Electrostatic precipitator is used to control Air pollution. An electrostatic precipitator is a filtration device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit.

A number of possible explanations for why manhole covers are round include :

1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole.

2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening.

3. A round manhole cover is easily moved and rolled.

4. Human beings have a roughly circular cross-section.

5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well.

6. It’s easier to dig a circular hole.