Calculate the angle of incidence when the incident ray makes an angle of 70 degree with the reflected ray.

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Which of the following would not be taken into consideration when describing the quality of a sound

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

Spend time observing or thinking about events that involve matter and energy. which events can you explain? which events can’t you explain?