Match physical quantities with their definitions.

a) energy        b) equilibrium           c) momentum d) power        e) work

1.  the product of mass and linear velocity of a body. It is thus a vector quantity.

2. a state in which mechanical, thermodynamic or other systems will remain if undisturbed.

3. alternative name for energy, used particularly in discussing mechanical processes.

4. to the economist, a synonym for fuel; to the physicist, one of the fundamental modes of existence, equivalent and interconvertible with matter.

5. the rate at which work is performed, or energy dissipated. Frequently in engineering (and particularly in transportation) contexts, what matters is the power that a given machine can deliver or utilize − the rate at which it can handle energy − and not the absolute energies involved.

Fill the gaps with the following words.

The Importance of Measurements in Physics

a)acquire b)apparent c)considering d)improved e)magnitude   f)meaningless   g)measurable   h)necessitate i)numerical  j)percentage   k)reading   l)reliable                m)resulted            n)sophisticated         o)taking

 

Accurate measurement is central to the development of any science. The importance of measurement was … (1) to ancient civilizations. Throughout history the accuracy with which measurements could be made has been … (2) by the use of more and more sophisticated instruments. At almost every stage, improved measuring techniques have … (3) in new concepts and ideas.

The science of physics, like all other sciences, is based on … (4)  measurements. All scientific laws and theorems must be tested experimentally, and all experiments … (5) making measurements. One of the reasons for the development of physics as a science is that the measurements that are made in physics are usually more … (6) than the measurements made in other sciences.

Physical quantity is the term that is used to include … (7) features of many different items. The area of a playing field, the mass of a bag of sugar and the speed of an aeroplane are all physical quantities.

In quoting any measurement of a physical quantity, two items need to be stated. The first is the … (8) value of the quantity, sometimes called the …(9), and the second is its unit. It is important at all times to think of and to write the value and the unit of any quantity together. Apart from technical accuracy of writing in this way, it will also help you to … (10) mental appreciation of the size of the quantity you are … (11).

For instance, if the diameter of the wire is found to be 1,46 meters, then something is wrong. A value stated as simply 1,46 is … (12). Realizing if the particular value is possible or not is something that comes with experience, but it is only by thinking about the sizes of physical quantities that this experience is gained.

Whenever a measurement of a physical quantity is made, some measuring instrument has to be used. The instrument may be as ordinary as a ruler or as … (13) as a modern mass spectrometer. In using the instrument an experimenter has to make use of his or her own skills to obtain as accurate … (14) as possible. Built-in to the instrument however is a limit of accuracy. The result of this is that the experimenter takes has a degree of uncertainty. The size of uncertainty needs to be considered together with the size of the quantity being measured. Uncertainties can be described as absolute, fractional and … (15) uncertainties.

 

4. WORD FORMATION: Academic English

Fill the table. Use a dictionary when necessary.

Dimensions and Parameters                                                        Table 9

verb	noun	adjective
	magnitude
measure
	length
		wide
deepen
		high
	strength
	weight
prolong
		large

MIND YOUR PRONUNCIATION

5. In which words is the letter b not pronounced?

1. doubt 2. debt  3. bomb 4. bombing 5. undoubtedly

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