1.3 : Scalar Quantities and Vector Quantities

1. Some physical quantities are used to describe the motion of objects.

2. These quantities can be divided into two categories :

a) Scalar quantityb) Vector quantity

i. Scalar quantity A girl walks 4 meters.Magnitude : _________Direction :__________

ii. Vector quantity A girl walks 4 meters

East.Magnitude : _________Direction : __________

1.3 : Scalar Quantities and Vector Quantities

i. Scalar quantity A girl walks 4 meters.Magnitude : 4 metersDirection : No

direction

ii. Vector quantity A girl walks 4 meters

East.Magnitude : 4 metersDirection : East

A scalar quantity is a physical

quantity which has magnitude only

A vector quantity is a physical quantity

which has both magnitude and

direction.

Do the exercise on Science Process Skill page 5

1.4 : MEASUREMENT

Measurement is the process of determining the value of a

physical quantity using scientific instruments

The length of an object can be measured by using a metre rule, vernier callipers or micrometer screw

gauge.

Accuracy in measurement is the degree of closeness of a measurement

value to the actual value

1.5 : ACCURACY, CONSISTENCY AND SENSITIVITY

A measurement with a smaller

percentage error has a

higher accuracy

Consistency (precision) is the

degree of uniformity or

reproducibility of the measurements.

inaccurate but consistent consistent and accurate

accurate but not consistent inaccurate and not consistent

Sensitivity is the ability of an instrument to detect small changes in the physical quantity being

measured

A measuring instrument which has smaller scale divisions is more

sensitive

A more sensitive measuring instrument is able to :

1. Detect very small changes in the physical quantity that is being measured.

2. Respond more quickly towards changes in the physical quantity that is being measured.

RANDOM ERRORS Uncertainties in the

measurement due to:

SYSTEMATIC ERRORS

Uncertainties in the measurement due

to:

1. Observer (parallax error)

2. The surroundings

3. The instruments

1. Observer 2. The surroundings3. The instruments

(zero error)

Repeat measurements (taking several readings)

and calculating the average

Using different instruments and taking

measurements carefully