Speed Unit Conversion ② How to Convert Kilometers per Hour (km/h) and Meters per Second (m/s)
Problems that switch between kilometers per hour and meters per second often appear in junior-high entrance examinations. Master “÷ 3.6” and “× 3.6.”
Key Point
- Kilometers per hour → meters per second: divide by 3.6 (the same as × 1000 ÷ 3600)
- Meters per second → kilometers per hour: multiply by 3.6 (the same as × 3600 ÷ 1000)
Example 1: How many meters per second is 90 km/h?
Solution: 90 ÷ 3.6 = 25 m/sec
Solution: 90 ÷ 3.6 = 25 m/sec
If you are unsure whether to multiply or divide, write the units and check.
1 km/hour = 1000 m ÷ 3600 sec = 1 ÷ 3.6 m/sec Therefore a km/hour = a ÷ 3.6 m/sec
Example 2: How many kilometers per hour is 8 m/sec?
Solution: 8 × 3.6 = 28.8 km/hour
Solution: 8 × 3.6 = 28.8 km/hour
Entrance examinations may also ask questions such as “What is the speed in kilometers per hour of a train traveling at □ meters per second?” Practice multiplying and dividing by 3.6 quickly.
Useful Numbers to Remember
36 km/hour = 10 m/sec
72 km/hour = 20 m/sec
108 km/hour = 30 m/sec
(Remember these as multiples of 36, and you can use them all at once.)
36 km/hour = 10 m/sec
72 km/hour = 20 m/sec
108 km/hour = 30 m/sec
(Remember these as multiples of 36, and you can use them all at once.)