If relativistic effects are to be less than 1%, then \(\gamma\) must be less than 1.01. At what relative velocity is \(\gamma=1.01\)?
Chapter 5 Notes The bigger the amplitude of pressure variations is, the bigger the energy that is being carried by the waves Energy carried by the wave is proportional to a square of amplitude- E- A^2 Power is the energy point per unit time P= E/T The unit of Power is the Watt (W) Power as a result, characterizes the ability of our source to emit waves but says little about how much energy is caught by a particular receiver Intensity is the power delivered to a particular point or l= P/s The intensity does not have special units and is measured just in units of power divided by units of area W/m^2 Intensity at any given point depends on the amplitude of a wave: proportional to the square of amplitude Increasing a distance from a source obviously decreases the loudness of the sound Intensity is indirectly proportional to the area which power of our source is distributed. If we increase the distance two times, we increase the area 4 times The law of dependence of intensity on the distance from a source is called the inverse square law. It describes not only the behavior of sound from a point source with distance but it is also valid for a point source of any nature: the gravitational field outside of a planet, electric field from a charge, intensity of light from a star For measurements of sound intensity levels or SIL we use the unit of decibels dB. This measures pressure variations in a wave. It measures the ratio of intensities, but not the amount of sound itself. If intensities are multiplied, SIL’s are added. Never Multiply SIL’s Environmental noise