definition,
acceleration the rate change velocity with time.Basic electrotechnical units and theory
85
Most modern machines can traced back the five basic machines
described the Greek inventor Hero Alexandria who lived about the
time Christ. The unit mass
is the kilogram (kg).81N (see also the definition ‘force’).
Velocity speed given direction.
Definition
By definition, acceleration the rate of
change velocity with time. Therefore, speed is
concerned with distance travelled and time taken.
. The machines described him were the wedge, the screw,
the wheel and axle, the pulley and the lever. The unit mass is
the kilogram (kg). Let now consider some fun-
damental mechanical principles and calculations. Normally exerts this force
because being attracted towards
the earth the force gravity.
In everyday conversation often use the word velocity mean the same
as speed, and indeed the units are the same.
Definition
Speed concerned with distance trav-
elled and time taken.
Weight
Weight measure the force which body exerts anything which
supports it. Normally exerts this force because being attracted
towards the earth the force gravity.
Definition
Mass measure the amount of
material substance, such metal,
plastic, wood, brick tissue, which
is collectively known body.
The feeling speed something with which are all familiar. travel
in motor vehicle know that increase speed would, excluding acci-
dents, allow arrive our destination more quickly.
Mass
Mass measure the amount material substance, such metal,
plastic, wood, brick tissue, which collectively known body.
Speed
Definition
Weight measure the force which
a body exerts anything which sup-
ports it. The
mass body remains constant and can easily found comparing it
on set balance scales with set standard masses. The
mass body remains constant and
can easily found comparing it
on set balance scales with set of
standard masses.
For scientific purposes the weight body not constant, because gravi-
tational force varies from the equator the poles; space body would be
‘weightless’ but here earth under the influence gravity 1kg mass would
have weight approximately 9. However, for sci-
entific purposes this not acceptable
since velocity also concerned with
direction.
Velocity
Distance (m)
Time (s)
Acceleration
When aircraft takes off, starts from rest and increases its velocity until
it can fly. Speed scalar quantity, while velocity vector quantity. Suppose were travel
a distance 30miles our speed would average 30miles/h:
Speed
Distance (m)
Time (s)
Velocity
Definition
Velocity everyday conversation we
often use the word velocity mean
the same speed, and indeed the
units are the same. However, for scientific pur-
poses this not acceptable since velocity also concerned with direction. Originally they were used for
simple purposes, raise water and move objects which man alone
could not lift, but today their principles are fundamental importance to
our scientific understanding mechanics. For example, the speed aircraft
might 200miles/h, but its velocity would 200miles/h in, say, west-
erly direction. This change velocity called its acceleration
