Chapter 1: Movement - Physics Form Five

Chapter 1: Movement – Physics Form Five

Measurement is the process of assigning numbers to a given physical quantity.

Physical Quantity

In describing the behavior of objects around us we have to consider to matter, space and time. A moving body covers distance with time and for an object to move energy is required.

For the motion to take place, force must be applied. When an object is in the course of motion changes its speed within a given time interval we said that it is undergoing acceleration.

In all this we have physical quantities which are measurable and whose values can be used in the mathematical expressions to give numerical description about the object in a question.

The physical quantitiesmare divided into two categories which are fundamental / basic quantities and derived quantities.

(a) Fundamental quantities

These are independent physical quantities such as mass, length and time. These quantities have both dimensions and standard units which can be expressed dimensionally.

The dimensions of mass, length and time are represented as M, L and T respectively. The term dimension is used to denote the nature of physical quantity.

(b) Derived quantities

The physical quantities which are obtained from fundamental quantities are called derived quantities. An example of derived quantities are such as area, volume, density, speed, and momentum. These quantities can be obtained by combining the fundamental quantities in one way or the other.

The following are the few examples:

(i) Area =Length Length

[A]= L × L =L2

(ii) Volume =Length × Length × Length

[V] = L × L × L

(iii) Density = Mass/Volume

[ρ] = M/V

(iv)Speed = Distance/Time

[V] = L/T =LT-1