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As, due to, because, so that, on the other hand, in addition to , since.

  1. a) We assume the machine operates uniformly.

b) There is no accumulation or depletion of energy within it.

  1. a) Efficiency is always less than unity.

b) Every device operates with some loss of energy.

  1. a) There is always some loss of energy in mechan­ical devices involving moving parts.

b) Kinetic friction forces do the negative work.

  1. a) Mechanical friction results in energy loss.

b) There may also be electrical and thermal energy loss.

  1. a) Efficiency is always less than unity.

b) Energy cannot be created within the machine.

  1. a) Any motor, no matter how small, can deliver a large amount of energy if given sufficient time.

b) A large and powerful machine is required to deliver a large amount of energy in a short period of time.

  1. a) The total work is not a measure of the capacity of a machine.

b) A motor of any size can deliver any amount of energy if given sufficient time.

Appendix 1.

Commonly used mathematical symbols and expressions.

+

plus; the sign of addition (знак сложения), positive

-

minus; the sign of subtraction (знак вычитания), negative

±

plus or minus/approximately

×

(is) multiplied by /times; multiplication sign

÷

(is) divided by; division sign; ratio sign

=

is equal to /equals ; sign of equality

is not equal to / does not equal to

<

is less than

is less than or equal to

>

is more than / greater than

is more than /greater than or equal to

%

per cent

log e

natural logarithm or logarithm to the base e

(square ) root

3

cube root (out ) of

n

n-th root (out ) of

x2

x [eks] squared

x3

x [eks] cubed

x4

x [eks] to the power four/ to the fourth power

dy/dx

derivative of y with respect to x

d2y/dx2

second derivative of y with respect to x

x

absolute value of x

the integral of

f (x) dx

the integral of a function of x over dx

mn

the integral between limits n and m

[]

brackets, square brackets

()

round brackets

 

is parallel to

is perpendicular to

right angle

apostrophy

,

comma

.

full stop

0

degree

a ′

a prime

a ″

a second prime or a double prime

a ′″

a third prime or a triple prime

b1

b sub one or b first

b2

b sub two or b second

lim

limit

sin

sine

cos

cosine

tan, tg

tangent

ctn,cot

cotangent

sec

secant

sin -1

antisine

cos-1

anticosine

f (x) or φ (x)

function of x

x

increment of x

dx

differential of x

0.1

zero point one

0.34

zero point three four

0.001

zero point zero zero one

one - eighth

¼

one quarter

½

one half

one third

¾

three-quarters

3/462

three over four-six-two

20/83

twenty over eighty-three

π

pi [pai]

r

[ α] – radius of circle

π r2

pi r squared [pai α skweәd ]

ε

summation

Appendix 2.

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