1) There must be a force
2) There must be displacement
Energy of the waves are redistributed to form a resultant wave with amplitude given by the summation of individual wave's amplitude.
<span>If the two waves are of same frequency, speed and amplitude and travelling in opposite direction den stationary waves are form.</span>
The coefficient of restitution is a measure of the interaction of the ball with the material of the ground. Since the ground is too solid to move (usually), or give way, the energy of the ball-ground system must be conserved in the main. Some of the energy is released as sound waves but the rest is given to, or reflected back to the ball and it follows the path of reflection. When the ball is dropped vertically it returns along the same path. So the force is actually the potential energy created by dropping converted to kinetic energy on collision with the ground. This is the origin of the force making it bounce.
First of all we know about the ionic bond that the attraction b/w two atoms the atom which lose electrons is become cation and have positive sing which one get electrons it become ionic. so in such sitivation the sodium lose one electons "that's why sodium has 1+ charge in Nacl chemacal bond."
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