Friction occurs between two contacting surfaces. The coefficient of friction is very much dependent on the roughness of these surfaces. Some of the many ways in which the coefficient can be lessened or decreased are to lubricate the surface or make it shiny by eliminating the spikes which caused the roughness.
The Wheel & Axle. The wheel has always been considered a major invention in the history of mankind
The Inclined Plane
The Wedge
The Pulley
The Screw
An electric power measure the rate of electrical energy transfer by an electric circuit per unit of time.
Sounds are created when something vibrates (shakes back and forth), sending waves of vibrations into the ears of the listener. When a bell is struck, the metal vibrates. The vibrations travel through the air as sound waves.
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