the students would be able of examining the natue of fluid

2. Dr.Ambreen Zahid
Senior lecturer

3.  What is fluid
 Relative Motion
 Relative velocity
 Types of flow
 Properties of fluid
 Buoyancy

4. FLUID
 substance that flows when subjected
to a shear stress
 Air and water are fluids that exert
forces on the human body.

5.  a fluid is a
substance that
continually deforms
(flows) under an
applied shear stress,
or external force.

6.  RELATIVE MOTION:
 The velocity of a body relative to a
fluid influences the magnitude of the
forces exerted by the fluid on the
body.

8. Relative velocity
 velocity of a body with respect to the
velocity of something else, such as
the surrounding fluid

10. Laminar flow
 flow characterized by smooth,
parallel layers of fluid
Turbulent flow
 flow characterized by mixing of
adjacent fluid layers

12. Factors that influence the
magnitude of the forces a fluid
generates are the fluid’s
 density
 specific weight

13.  viscosity, density (defined as
mass/volume),
 ratio of weight to volume is known
as specific weight.
 Increased fluid viscosity results in
increased forces exerted on bodies
exposed to the fluid.

14. Atmospheric pressure and
temperature influence a
 fluid’s density
 specific weight
 viscosity, with more mass
concentrated in a given unit of fluid
volume at higher atmospheric
pressures and lower temperatures.

15.  molecular motion in gases increases
with temperature, the viscosity of
gases also increases.
 The viscosity of liquids decreases
with increased temperature because
of a reduction in the cohesive forces
among the molecules.

16.  Buoyancy is a fluid
force that always
acts vertically
upward.

17.  The factors that determine the
magnitude of the buoyant force
were originally explained by the
ancient Greek mathematician
Archimedes.

18. The magnitude of
the buoyant force
acting on a given
body is equal to the
weight of the fluid
displaced by the
body.

20.  Buoyancy (Fb) is calculated as the
product of the displaced volume (Vd)
and the fluid’s specific weight (ɣ).
Fb = Vdɣ

21.  For example, if a water polo ball with a
volume of 0.2 m3 is completely
submerged in water at 20°C, the
buoyant force acting on the ball is equal
to the ball’s volume multiplied by the
specific weight of water at 20°C:
Fb = Vdɣ
(0.2 m3) (9790 N/m3)
5 1958 N

22.  The more dense the surrounding
fluid, the greater the magnitude of
the buoyant force.
 seawater is more dense than
freshwater

24.  point around which a body’s volume
is equally distributed and at which
the buoyant force acts, which is also
known as the center of buoyancy

26. Any Questions….???