Physics: [Unit 1: Physical Quantities, Units and Measurement]

Try to remember 5 terms:

Prefix (nano) Symbols (n) Factors (10^-9) Value (0.000000001) Scale (billionth)

Define Physical Quantity?

Property of object that can be measured by an instrument.

Define Vector Quantity?

Quantity that has both magnitude and direction.

Scalar quantity

Quantity that has magnitude only `

SI unit of length

metre (m)

Advantage of measurements in the SI Units?

Allows the measurements made in different parts of the world to be uniformn and standardised.

No prefix

Base unit *most si unit are base units except kg*

Define Length?

Distance between two points

Advantage of Prefixes?

Efficient way to represent very small or very large number in the measurement.

Define Prefixes?

(T +12) G +9 M +6 K +3 d -1 c -2 m -3 m* -6 n -9 (p -12)

4 Precautions of Metre Rule?

1. Make sure that is no gap between metre rule and object to be measured. 2. Avoid end error (caused by the damage of both ends of the metre rule) by checking the physical condition of the metre rule 3. Avoid zero error by placing the object exactly on the O marking of the scale (Positive zero error: The object is placed after the O marking of the scale which causes the measurement to appear greater) (Negative zero error: The object is placed before the O marking of the scale which causes the measurement to appear smaller) 4. Avoid Parallax error by placing eye vertically above the mark of the scale when taking the reading (Parallax error is an error in reading a measuring instrument when the eye of the observer is not directly above the markings of the measuring instrument)

5 lab instruments?

1. Measuring Tape 2. Metre Rule 3. External and Internal Calipers 4. Vernier Calipers 5. Micrometers

Measurement consists of 2 things

Magnitude and Unit

Define Magnitude?

Numerical magnitude of a quantity.