Scientists use all sorts of units of measurements to get values and quantities. Some of these are called fundamental quantities and some of them are called derived values. What is the difference between the two different kinds of measurements?
Fundamental values
Fundamental quantities are the base units in a given measurement system. They can also be directly measured.
These types of values have something in common. They can all be directly measured.
1. Distance. How far did you travel? One thousand meters.
2. Time. How long did it take to travel here? 3,600 seconds.
3. Volume. How much milk is in the jug? One liter.
4. Temperature. The temperature at which atoms cease to move is 0 Kelvins. Temperature can be measured in degrees above Kelvin. The temperature outside, on a cold day, might be 273.15 Kelvin.
Derived quantities
While fundamental quantities can be directly measured, derived ones must be calculated. They are calculated from the base unit. That’s the biggest difference. Examples of derived quantities include:
1. Speed. You might be able to see your speed on the speedometer on your car, but it is a derived value. Speed is calculated by dividing total distance traveled by the time it took to travel it. So, if you traveled 100 miles in two hours, your rate, or your speed, was 50 miles per hour. If you traveled 150 kilometers in 3 hours, then your speed was 50 kilometers per hour.
2. Celsius and Fahrenheit. Zero degrees Celsius is 273.15 Kelvin. Zero degrees Fahrenheit is 255.37 Kelvin. Kelvin is the base unit in the SI system. However, it is much easier to measure Celsius and Fahrenheit, but they are still considered to be derived.
3. Watts. That is a 100 Watt light bulb. What does that mean? Watts are power, otherwise known as radiant flux. It’s the amount of all the light including infrared, ultraviolet, and visible. Watts are calculated by dividing the Joules by seconds, so a Watt is a J/s.
4. Joules. Joules are also a derived quantity and a Joule is the amount of energy it takes to exert 1 Newton of force for one meter. Joules are an amount of energy. Another unit for measuring energy, more common in the non-scientific world, is the calorie. A calorie is the amount of energy required to raise the temperature of one milliliter of water one degree Celsius at standard temperature and pressure. The calories listed on the back of food packages are actually Kilo-calories.
5. Newton. A newton is also a derived value. A newton is the net force required to accelerate one kilogram of matter one meter per second. Finally, a couple of fundamental quantities. A meter is the fundamental distance in the SI system, and a second is the base unit of time. A kilogram is still a derived quantity.
6. Kilogram. Mass, when measured in grams, is a fundamental quantity. Kilograms, however, are one thousand grams, so kilograms are derived.
When you’re working with the metric system, the fundamental unit is the base of the word. Grams are fundamental. Kilograms are derived. Meters are the base. Kilometers are derived. A liter is the base and a milliliter is derived. A derived number comes about through a calculation, even if it is as simple as multiplying something by 100.
