A one or two letter abbreviation for a chemical element.

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.

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant

Acar travels 40m in 8 seconds find the car speed