Knowledge N Fact4u

Why is plastic not used in home construction ? •Plastic materials are used in several ways in home construction. Plastic has useful properties such as water resistance, corrosion resistance, electrical insulation, and durability. •Here we are using the common meaning of the word "plastic": a synthetic moldable solid. Among the uses of plastic in home construction are: •Sewage pipes. These are increasingly being made out of plastic such as PVC instead of metal because PVC is cheap, corrosive resistant, light, and somewhat flexible. •Water supply lines. These are increasingly being made out of plastic such as PEX because PEX is cheap, strong, and flexible. The relatively high flexibility of PEX leads to better water flow and quicker installation. •Fuel supply lines. •Electrical conduits. These are channels that carry various electrical wires. •Insulating coating on electrical wires. •Housewarp. This is the weather barrier that is placed just behind the

Why are stars not blurred even though the earth is moving ? •Stars are blurred when viewed from earth. We just don't notice it much with our naked eyes because of the high temporal and low spatial resolution of the human visual system. •Take a glow stick, sparkler, or flashlight and spin it very quickly in the dark. You don't see an individual object anymore, but see instead a circular blur of light. •The reason for this is that the spin rate is faster than the rate at which our eyes can discern distinct images.  •The distinct images of the object get smeared together in a process known as motion blur.  •So why don't the stars look like spinning glow sticks? The rotation of the earth does cause the stars to spin in the sky, but the spinning is much slower. •Whereas it takes the stars one day to trace out a circular path in the sky, it takes tenths of a second for the glow stick to spin in a circle.  •Our eyes can mostly keep up with the motion of the stars because