Convert 90 km/h to metres per second

Question

Solve in your head. What is 90 km/h in metres per second? Aim: under 5 seconds.

Accepted Answer

One hour is 3600 seconds and one kilometre is 1000 metres, so 1 	ext{ km/h} = \frac{1000}{3600} 	ext{ m/s} = \frac{1}{3.6} 	ext{ m/s}. Divide by 3.6: \frac{90}{3.6} = \frac{900}{36} = 25 	ext{ m/s}. Takeaway. Memorise the factor 3.6 in both directions: km/h 	o m/s divide by 3.6; m/s 	o km/h multiply by 3.6. Useful anchors: 36 km/h = 10 m/s, 72 km/h = 20 m/s, 108 km/h = 30 m/s. (The imperial cousin: 60 mph = 88 ft/s.)

Convert 90 km/h to metres per second

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