SI Units

Question 1

What are the needs for SI unit measurements

Answer 1

Standardise measurements
Internationally agreed
Ensure accuracy
Ensures comparable & consistent measurements
Ensures confidence & trust in measurements

Question 2

What are base units

Answer 2

Length = metre (m)
Mass = kilogram (kg)
Time = second (s)

Question 3

SI unit components

Answer 3

Prefix
Unit symbol
Exponent

Question 4

What are derived SI units

Answer 4

Produced from combination of SI base units

Always contain at least one base unit: m, kg or s

Examples: newton (N) and joule (J)

Question 5

Quantities

Answer 5

Vector - direction & magnitude
Scalar - magnitude
Force - initiates movement or alters speed/direction
Energy - ability to do work/make something happen
Work - energy transferred when a force moves
Power - rate of doing work/rate of using energy

Question 6

When is it appropriate to use non-SI units

Answer 6

Cultural norms - eg: drinks (pint), food (calories)

SI unit too large/small

Non-SI units in hospital context - eg: Bp (mmHg)