What Is Centimeter per Hour (cm/h)?
Centimeter per hour is a unit of speed. It tells you how many centimeters something travels in one hour. It is used for very slow movement, like plant growth or slow dripping water.
Because it uses centimeters and hours, cm/h is part of the metric system and fits well with other metric units like meters and kilometers.
Definition
Centimeter per hour (cm/h) is the speed of an object that moves one centimeter in one hour.
In simple math form:
1 cm/h = 1 centimeter of distance / 1 hour of time
We can also write it using meters and seconds:
- 1 centimeter = 0.01 meter
- 1 hour = 3,600 seconds
So:
1 cm/h = 0.01 meter / 3,600 seconds ≈ 0.00000278 m/s
That number is very small, so cm/h is only used when things move very slowly.
History / Origin
Centimeter per hour comes from two older ideas: the centimeter and the hour.
- The meter was created in France in the late 1700s as the main unit of length for the metric system.
- The centimeter was later defined as one hundredth of a meter.
- The hour is a very old time unit, used in many cultures, and is equal to 60 minutes or 3,600 seconds.
People needed a way to talk about very slow speeds inside the metric system. By combining centimeter for distance and hour for time, they formed the unit centimeter per hour, written as cm/h.
Symbol & Abbreviation
The standard symbol for centimeter per hour is:
- cm/h
You may sometimes see it written in other ways in science texts, such as:
- cm h−1 (means centimeters times hour to the power of minus one)
- cm per h (spelled out)
All of these mean the same thing: centimeters divided by hours.
Try not to confuse cm/h with units like km/h (kilometer per hour) or m/s (meter per second), which describe much faster speeds.
Current Use Around the World
Centimeter per hour is not common in daily life, because most things we see move much faster. However, it is still useful in some special areas:
- Biology and botany to describe plant growth or slow movement of roots.
- Geology and earth science to show how fast soil, sand, or mud slowly moves.
- Hydrology to measure very gentle water seepage into the ground.
- Medicine and labs for slow drip rates in some tests or equipment.
In most countries, people use m/s (meters per second) in science and km/h (kilometers per hour) or mph (miles per hour) in daily life. Centimeter per hour is kept for cases where these units would give very tiny decimal numbers.
Example Conversions
To use centimeter per hour well, it helps to know how to change it into other speed units.
Basic conversion rules
- 1 cm = 0.01 m
- 1 cm = 0.00001 km
- 1 h = 60 min = 3,600 s
From cm/h to m/s
Formula:
m/s = cm/h × 0.00000278 (approx)
Examples:
- 1 cm/h ≈ 0.00000278 m/s
- 100 cm/h ≈ 0.000278 m/s
- 10,000 cm/h ≈ 0.0278 m/s
From cm/h to km/h
Formula:
km/h = cm/h × 0.00001
Examples:
- 1 cm/h = 0.00001 km/h
- 100 cm/h = 0.001 km/h
- 50,000 cm/h = 0.5 km/h
From cm/h to cm/min
Formula:
cm/min = cm/h ÷ 60
Examples:
- 60 cm/h = 1 cm/min
- 120 cm/h = 2 cm/min
From cm/h to mm/s
Since 1 cm = 10 mm:
mm/s = cm/h × (10 / 3,600) ≈ cm/h × 0.00278
Example:
- 100 cm/h ≈ 0.278 mm/s
From cm/h to mph (miles per hour)
1 mile ≈ 160,934.4 cm, so:
mph ≈ cm/h ÷ 160,934.4
Examples:
- 1 cm/h ≈ 0.00000621 mph
- 10,000 cm/h ≈ 0.0621 mph
Related Units
Here are some other speed units that are related to centimeter per hour:
- Centimeter per second (cm/s) similar unit but uses seconds instead of hours, good for faster motion than cm/h.
- Meter per second (m/s) main speed unit in science and engineering in the metric system.
- Kilometer per hour (km/h) common for car speeds and road signs.
- Millimeter per hour (mm/h) even smaller than cm/h, sometimes used for rainfall rates.
- Inch per hour (in/h) non metric unit for very slow motion or rainfall in some countries.
- Mile per hour (mph) everyday speed unit in the United States and a few other places.
All of these units describe the same idea: how far something moves in a certain time, only the size of the length and time units change.
FAQs
Q: What does 1 cm/h mean in simple words?
A: It means that something moves 1 centimeter in one hour. This is a very slow speed, slower than a snail.
Q: Why would anyone use centimeter per hour?
A: People use cm/h when things move so slowly that common units like km/h or m/s would give tiny, hard to read numbers. It is helpful for plant growth, soil movement, or slow drips.
Q: Which is faster, 1 cm/h or 1 cm/s?
A: 1 cm/s is much faster. In one hour, 1 cm/s would cover 3,600 centimeters, while 1 cm/h covers only 1 centimeter.
Q: How can I quickly change cm/h to km/h?
A: Divide the number in cm/h by 100,000, or multiply by 0.00001. For example, 25,000 cm/h is 25,000 × 0.00001 = 0.25 km/h.
Q: Is cm/h an SI unit?
A: It uses SI based units, centimeter and hour, but it is not the main SI speed unit. The main SI speed unit is meter per second, written as m/s.
Q: Can I use cm/h in school science work?
A: Yes, you can. However, teachers and textbooks usually prefer m/s. If you measure something in cm/h, you may be asked to convert it to m/s.
Q: How do I know which speed unit to choose?
A: Use m/s or km/h for normal motion like walking or driving. Use cm/h or mm/h when movement is very slow, such as growth, slow drips, or tiny shifts in the ground.
