What is meant by coefficient of something like there are coefficient of thermal conductivity and so on.

Describe the path of a ray that approaches a mirror parallel to the principal axis.

Phase changes are chemical changes. true or false

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.