● ‘Centrifugal force’ the force acting away from the centre, the oppo-
site centripetal force.
6
6 2
kN/m
Example 2
A small circus elephant mass tonne (1000kg) puts all its weight one foot which has
a surface area 400cm2
.
● ‘Magnetic force’ the force created magnetic field. Calculate the pressure exerted the shoe the floor (assuming the
acceleration due gravity 9.
Pressure
Force
Area
(N/m )
Pressure
kg m/s
m
2
2
4 2
1000 81
400 10
.
245 3
.
● ‘Electrical force’ the force created electrical field. Calculate the pressure exerted the elephant’s foot the floor,
assuming the acceleration due gravity 9. Heavy breathing and perspiration would evidence the work done.
Pressure stress
To move broken-down motor car might exert force the back the
car propel forward. This because her mass exerts force over much smaller area
than the elephant’s foot and the reason why many wooden dance floors are damaged by
high-heeled shoes.
● ‘Gravitational force’is the force
acting towards the centre the
earth due the effect gravity. hands would apply pressure the body
panel the point contact with the car. kN/m2
These two examples show that the young woman exerts times more pressure the
ground than the elephant.
Definition
Pressure stress measure the
force per unit area.
● ‘Centripetal force’ the force acting towards the centre when mass
attached string rotated circular path.
● ‘Friction force’is the force which
resists prevents the movement
of two surfaces contact. Pressure stress measure of
the force per unit area.
● ‘Centrifugal force’is the force
acting away from the centre, the
opposite centripetal force.
● ‘Gravitational force’ the force acting towards the centre the
earth due the effect gravity.
●
‘Electrical force’is the force created
by electrical field.
● ‘Cohesive adhesive force’is
the force required hold things
together.
Definition
● ‘Inertial force’is the force required
to get things moving, change
direction stop, like the motor
car discussed above.
● ‘Compressive force’is the force
pushing things together.81m/s2
.
● ‘Tensile force’is the force pulling
things apart.
● ‘Centripetal force’is the force
acting towards the centre when
a mass attached string is
rotated circular path.81m/s2
).
● ‘Magnetic force’is the force
created magnetic field.
● ‘Shearing force’is the force which
moves one face material over
another.Basic electrotechnical units and theory
87
● ‘Shearing force’ the force which moves one face material over
another.
.
Pressure stress
Force
Area
N/m
)
2
Example 1
A young woman mass 60kg puts all her weight the heel one shoe which has
an area 1cm2
.
Pressure
Force
Area
(N/m )
Pressure
kg m/s
m
2
2
4 2
60 81
1 10
588
.
Work done
Suppose broken-down motor car was pushed along road, work
would done the car applying the force necessary move along the
road
