Question

Express: $2.25m{\text{ in }}cm$

Answer 1

At first, we discussed the definition of physical quantities. Then we use the measurement scale of the meter. Also,we have to convert one meter to a centimeter. Finally we put the given value in the meter unit to get this in the centimeter unit.

Formula used:
$1m = 100cm$

Complete step by step answer:
The unit is used to measure any physical quantities in comparison with others. The unit is different and unique for different physical quantities. The unit denotes the standard amount of a particular quantity.
The units for three physical quantities mass, length, and time are in mainly three systems each.
CGS - In this system, the centimeter is the unit of length, the gram is the unit of mass and the second is the unit of time.
S.I – In this system, the meter is the unit of length, the kilogram is the unit of mass and the second is the unit of time.
FPS- In this system, the foot is the unit of length, the pound is the unit of mass and the second is the unit of time.
Now the meter scale of length is like the following:

The units are in equidistance and the amount of each gap is $10$unit.
Hence $1{\text{ kilometer(km) = 10 hectometer(hm)}}$
Similarly, $1{\text{ meter(m) = 10 decimeter(dm)}}$
And $1{\text{ decimeter(dm) = 10 centimeter(cm)}}$
So, $1{\text{ meter(m) = 10 }} \times {\text{10 centimeter (cm) = 100cm}}$
We have to convert $2.25m{\text{ in }}cm$,
Since, $1{\text{m}} = 100{\text{cm}}$
$\therefore 2.25{\text{ m = 2}}{\text{.25}} \times {\text{100 cm = 225 cm}}$

Additional Information:
The measurement of length is divided into two methods – 1. Direct method and 2. Indirect method.
Direct method: In this method, the length of the sample is compared to the standard unit directly to measure its length. Such us, you can measure the length, breadth, and height of a book using a scale. In this method, we can also use the vernier scale, screw gauge, etc.

Indirect method: All the lengths can not be measured through the direct method, such as the distance of stars, or radius of molecules. These types of measurements are done through an indirect method like the Triangulation method, Reflection or Echo method, Parallax method, etc.

Note: We see that in the meter scale there are many types of units like kilometer(km), hectometer(hm), decameter(dam), meter(m), decimeter(dm), centimeter(cm), and millimeter(m).
The existence of many types of units is because of the measurement of different types of physical quantities i.e large amounts or small amounts.
Such as, if we need to measure a length of a standard size of a book we use the meter, centimeter but if we use a large unit like a kilometer or small unit millimeter we need to write a number with many digits. Similarly, for a distance, we generally use a kilometer instead of the centimeter or the millimeter as they are small units. That’s why the conversion of units is necessary.