Answers

2015-03-05T22:21:50+05:30
Work (W) is said to be done, when a force (F) acts on the body and point of application of the force is displaced (s) in the direction of force.
Work done = force x displacement 
W = F x s
ENERGY - The energy of the body is defined as its capacity to do workUnit of energy - Energy is measured in terms of work. Unit of energy is also joule. One joule of energy is required to do one joule of work
egaphone is a technology that is commonly used for announcements in public, it amplifies the voice of the speaker as loud as he wants.Megaphones, Horns and Loudspeakers: megaphones, horns (in cars, buses, etc.) and loudspeakers propagate sound in a particular direction. These instruments are specially designed with a conical opening in front of a small tube. Multiple reflections of sound from the conical part help in guiding the sound in a particular direction towards the audiences. These objects are used to address small gathering of people. 
An echo is the phenomenon of repetition of sound of a source by reflection from an obstacle. To distinguish an echo from the original sound, the obstacle must be situated at a suitable distance from the source of sound. This depends upon the type of sound produced, which may be simple or articulate.
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2015-03-05T22:22:54+05:30
The power produced by the motion of an object (work) is commonly called kinetic energy. Megaphone is a technology that is commonly used for announcements in public, it amplifies the voice of the speaker as loud as he wants. An echo occurs when the sound waves hits an oblique object or medium and sends it back.
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