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