What is used to measure mass?

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.

What is the final velocity of the initial velocity of 25 and -50?

What are similarities and differences of reflection, refraction, diffraction and absorption?