1 kilometer per hour = 0.27777778 m/s
1 km/h = 0.277778 m/s · type math like (12*4)+6.5
Km/h to meters per second is essential for physics problems, braking-distance calculations and engineering. Everyday speeds are in km/h, but formulas need SI units.
Physics homework almost always requires this conversion. Kinetic energy, momentum and stopping distance formulas need speed in m/s. A 1,500 kg car at 100 km/h (27.78 m/s) has kinetic energy of ½ × 1,500 × 27.78² = 578,700 J.
Road safety research uses it too. Reaction time of 1.5 s at 50 km/h means a car travels 20.8 m before braking starts, while at 100 km/h it travels 41.7 m. Doubling the speed doubles reaction distance and roughly quadruples braking distance.
Rail engineers calculate signal spacing and braking in m/s. A train at 300 km/h travels 83.3 m every second, so it covers a kilometer in 12 seconds.
Wind tunnel testing in automotive and cycling uses m/s. A cyclist at 45 km/h faces airflow of 12.5 m/s, and aerodynamic drag increases with the square of that speed.
Athletics comparisons often use both units. A sprinter running 100 m in 10 seconds averages 10 m/s, which is 36 km/h. Usain Bolt's 9.58 s world record averages 10.44 m/s, or 37.58 km/h, with a peak of about 44.7 km/h.
Elevators, escalators and moving walkways are specified in m/s even in countries where people think in km/h. A typical escalator moves at 0.5 m/s, which is 1.8 km/h, slower than walking pace of about 5 km/h.
Weather instruments such as anemometers usually output m/s. A forecast of 40 km/h wind corresponds to 11.1 m/s, which is a strong breeze on the Beaufort scale, enough to make umbrellas difficult to use.
Rollercoasters are often described in km/h but engineered in m/s. A coaster reaching 150 km/h is moving at 41.7 m/s. Engineers use the m/s figure to calculate g-forces in loops and turns.
Wind loads on buildings are calculated from wind speed in m/s. A design wind speed of 162 km/h is 45 m/s, and pressure on a wall increases with the square of that number.
To sanity-check, the m/s figure should be just over a quarter of the km/h figure. 72 km/h should come out at exactly 20 m/s, and 18 km/h at exactly 5 m/s. If your answer is larger than the km/h figure, you multiplied by 3.6 instead of dividing. Physics teachers often recommend memorising 36 km/h = 10 m/s as an anchor, since it makes checking any result fast. Engineers also keep a few extra decimal places during intermediate steps and only round the final answer.
m/s = km/h × 0.2777777778
Reverse: 1 m/s = 3.6 km/h.
How many meters does a car at 90 km/h travel each second?
Answer: 90 km/h = 25 m/s.
| km/h | m/s |
|---|---|
| 1 km/h | 0.27777778 m/s |
| 2 km/h | 0.55555556 m/s |
| 3 km/h | 0.83333333 m/s |
| 4 km/h | 1.1111111 m/s |
| 5 km/h | 1.3888889 m/s |
| 6 km/h | 1.6666667 m/s |
| 7 km/h | 1.9444444 m/s |
| 8 km/h | 2.2222222 m/s |
| 9 km/h | 2.5 m/s |
| 10 km/h | 2.7777778 m/s |
| 11 km/h | 3.0555556 m/s |
| 12 km/h | 3.3333333 m/s |
| 13 km/h | 3.6111111 m/s |
| 14 km/h | 3.8888889 m/s |
| 15 km/h | 4.1666667 m/s |
| km/h | m/s |
|---|---|
| 16 km/h | 4.4444444 m/s |
| 17 km/h | 4.7222222 m/s |
| 18 km/h | 5 m/s |
| 19 km/h | 5.2777778 m/s |
| 20 km/h | 5.5555556 m/s |
| 25 km/h | 6.9444444 m/s |
| 30 km/h | 8.3333333 m/s |
| 40 km/h | 11.111111 m/s |
| 50 km/h | 13.888889 m/s |
| 75 km/h | 20.833333 m/s |
| 100 km/h | 27.777778 m/s |
| 250 km/h | 69.444444 m/s |
| 500 km/h | 138.88889 m/s |
| 1 000 km/h | 277.77778 m/s |
At 90 km/h a car covers 25 m every second.
A 30 km/h cyclist moves at 8.33 m/s.
320 km/h is 88.9 m/s.
Kinetic energy ½mv² with v in km/h is off by a factor of 12.96. Convert first.
That goes the other way. Divide km/h by 3.6.
0.3 overstates by 8%. Use 0.27778.
1 km/h = 0.27778 m/s.
Origin. Metric road speed unit.
Used today. Car speeds, limits and cycling.
SI unit of speed.
Origin. Derived from the meter and the second.
Used today. Physics equations, anemometers and ballistics.
27.78 m/s.
Exactly 10 m/s.
At 100 km/h you travel 55.6 m in 2 seconds, enough to brake in normal conditions.
13.89 m/s.