Chapter 1- Measurement Flashcards
What is a physical quantity?
A physical quantity is a quantity that can be measured. It consist of a numerical magnitude and a unit.
What is physics?
Physics is the study of natural world - from very large ( e.g. solar system ) and to very small ( e.g. Atom)
Or
Physics is the study of matter and energy. These can be studied in the terms of their properties and relationship with each other in the field of General physics; thermal physics; light,waves and sound; electricity and magnetism.
Who many basic physical quantities?
There are 7.
The seven basic quantities, their SI units and their symbols
Base quantity Si unit Symbol for SI unit
Length Meter. M
Mass. Kilogram. Kg.
time. Second. S
Electric current. Ampere. A.
Temperature. Kelvin K
Luminous intensity. Candela. Cd
Amount of substance. Mole. Mol
Why is SI unit needed?
When we did not had them, the measurement changed from individual to individual. So in 1968 the scientists agreed to adopt on universal set of units
What is a SI unit?
SI units are the units of measurements in the widely used international system of Units.
What is the PREVISION of an instrument?
The smallest unit an instrument can measure is know as its precision.
How do we avoid the errors of measurement when using a meter rule?
When you use the meter rule, your eyes should be positioned such that your line of sight is perpendicular to ruler. Measurement errors introduced when this is not done are called parallax errors.
Define vernier caliper and its precision.
A pair of vernier calipers has a main scale and a sliding vernier scale. it is a useful tool for measuring both the internal and external diameters of an object. They have the precision of 0.01 cm.
Define the micrometer screw gauge and its precision
The micrometer screw gauge has a main scale and a thimble scale. It is usually used
- to measure objects that are too small to be measured with vernier caliper;
- when measurements to a precision of 0.01 mm (i.e. 10 micrometer) are required.
