4. A. Discuss the machine details using special terms as well as the connective and introductory words.

1. Definition of a cam and its characteristics. 2.Cams classification. 3.Calculations of the cams kinematic pairs for strength.

1) to act, load, angle, motion, axis, moving, bearing, to rotate, to carry, to support, to confine, journal, wear, wheel.

2) proceeding from, according to, considering, taking into consideration, taking into account, dealing with, provided, connected with, in connection with,

in accordance with, in relation with, regarding, as for, as to, concerning.

B.Discuss the mechanical devices that take advantage of friction. Include some that are not mentioned in the texts.

5. Read and translate the text. Add what you know on the topic

using the introductory words.

Functions

Leibniz (1646-1716), who first used the word "function", the notion of function was identified with the simple formula expressing the exact nature of relationship. All modern mathematics centres around the concept of function. The. concept of function is of the greatest importance not only in pure mathematics but also in practical applications. Physical laws are statements concerning the way in which certain quantities depend on others when some of these vary. The task of the physicist is determining the exact or approximate nature of this functional dependence. An expression such as x² + 2x ─ 3 has no definite numerical value until the value of x is assigned.

We say that the value of this expression is a function of the value of x, and write x² + 2x ─ 3 = ƒ(x)

For example, when x = 2 then

2² + 2 • 2 ─ 3 = 5, so that ƒ(2) = 5.

In the same way we may find by direct substitution the value of f{x) for any integral, fractional, irrational, or even complex number x.

The area of a triangle is a function of the lengths of its three sides; The atmospheric pressure is a function of the altitude above sea level. The whole domain of periodic phenomena — the motion of the

tides, the vibrations of a plucked string, the emission of light waves ─ is governed by the simple trigonometric func­tions sinx and cosx.

6. Make a summary of the text, use 'since' or 'because'

wherever possible.

UNIT 8

1. Learn the notions and their definitions.

Washer A flat disc, ring of metal, rubber etc., locking a nut in a place.

Shaft A machine part supporting and confining a moving part.

Gear A toothed wheel designed for being engaged with another one or with a warm.

Spur Gear A gear with straight teeth parallel to the axis.

Pinion The smaller member of a pair of gears or the smallest gear of a series; gear is used to designate the larger member.

Helical Gear A gear with teeth cut in the shape of a helix

Herringbone Gear A helical gear with two sets of teeth at equal

but opposite angles to each other.

Bevel Gear A gear with teeth slanted at an angle to the plane of the

wheel itself.

Worm Gear A mechanism consisting of a gear that meshes with a

worm, a screw with helical teeth.

Sun-and-Planet Gears An arrangement in which a smaller gear (the planet) rotates around a larger gear (the sun).

Casing, housing A machine covering

Bearing That part of a machine which supports parts in relative

Motion.

Text 1