Speed Unit Conversion Convert what quantity? From: centimeter/secondfoot/secondinch/secondkilometer/hourkilometer/secondknotmachmeter/secondmile/hour (mph)mile/secondmillimeter/secondspeed of light [vacuum]speed of sound [air] To: centimeter/secondfoot/secondinch/secondkilometer/hourkilometer/secondknotmachmeter/secondmile/hour (mph)mile/secondmillimeter/secondspeed of light [vacuum]speed of sound [air] Result: