速度单位换算

{"mps":{"label":"米\/秒","symbol":"m\/s","factor":1},"kmph":{"label":"公里\/小时","symbol":"km\/h","factor":0.2777777777777778},"mph":{"label":"英里\/小时","symbol":"mph","factor":0.44704},"kn":{"label":"节","symbol":"kn","factor":0.5144444444444445},"fps":{"label":"英尺\/秒","symbol":"ft\/s","factor":0.3048},"mach":{"label":"马赫（海平面）","symbol":"Mach","factor":340.29}}