Subiecte
G Amswer the following questions:
2. "What is meant by measurement?
2 What do you understand by the term unit?
State two characteristics of a standard unit.
4 Define length. What is its SI unit?
5 Name two devices used for measuring length.
6. What is mass?
7. Name two multiples and two submultiples of the unit of mass.
8. Define standard metre.
9. What is time? What is its SI unit?
10. Name two devices used to measure time.
11. What do you mean by temperature? State the SI unit of temperature.
Answers
Answer:
1. Measurement is the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events. The scope and application of measurement are dependent on the context and discipline. ... The science of measurement is pursued in the field of metrology.
2. In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method. A standard system of units facilitates this.
Following are the important characteristics of standard unit: (i) It should be easily understandable. (ii) It should be changed with change in physical factors. (iii) It should not change with place or time.
3. Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit for length is chosen, from which all other units are derived. In the International System of Units system the base unit for length is the metre.
S.I. unit: Metere(m)
4. Length: Tools used to measure length include a ruler, a Vernier caliper, and a micrometer screw gauge. Vernier calipers and micrometer screw gauges are more precise and can be used to measure the diameter of objects like pipe and wire.
5. Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied. An object's mass also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram.
6. Multiple units: Mega gram , Giga Gram ,Stone , Ton , Quintal , etc. Used for measuring heavy weights like lorries,flats etc. Submultiple units:Gram , Centigram , Decigram , Milligram , Nanogram , Microgram , etc. Used for measuring very light weights like bacteria , pins etc.
7. The metre is defined as the length of the path travelled by light in a vacuum in 1299 792 458 of a second. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km.
8. Time is the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future. ... Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition.
S.I. unit of time is Second(s)
9. Clock, sun dial
10.Temperature (symbolized T ) is an expression of heat energy. Temperature can mean different things in different situations. Thermodynamic temperature is a measure of the kinetic energy in molecules or atom s of a substance. ... The kelvin is the unit of temperature in the International System of Units ( SI ) is Kelvin(K)
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