Which of the following statements describes what happens when a sound wave moves from air into water?
a. The speed of the sound wave increases.
b. The speed of the sound wave decreases.
c. The frequency of the sound wave increases.
d. The wavelength of the sound wave decreases.

Which statement is true for light passing into a medium that is more optically dense than the first medium through which it past

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

3. which is not a primary color of light? blue red green yellow