2. Human movement in fluid
medium
Both air and water are fluid mediums
that exert forces on bodies moving
through them. Some of these forces
slow the progress of a moving body;
others provide support or propulsion.
Human movement in a fluid medium
involves the coordinated motion of the
body through substances like air or
water, influenced by
buoyancy and resistance.
3. Example
Swimming exemplifies human
movement in water, employing
coordinated strokes. Paragliding
showcases movement through air,
utilizing wind currents for controlled
flight.
4. Nature of fluids
Fluids, like water and air, exhibit flow and
take the shape of their container, offering
buoyancy and resistance in human
movement.
Examples
Buoyancy in Swimming: The upward
force of water supports the body,
enabling swimming and influencing
floating and diving.
Wind Resistance in Skydiving: Air
resistance affects the descent speed of a
skydiver, highlighting the impact of fluid
dynamics.
5. Laminar versus and Turbulent
flow
Laminar flow is smooth and orderly, with
parallel layers, while turbulent flow is chaotic,
featuring irregular and unpredictable
movement, common in high-speed fluid
dynamics.
Examples
Laminar Flow: Water flowing gently in a
straight, narrow stream maintains smooth,
parallel layers, exemplifying laminar flow.
Turbulent Flow: Rapids in a river create
chaotic, swirling patterns as water encounters
obstacles, demonstrating turbulent flow
dynamics.
6. Fluid properties
Fluid properties encompass
characteristics like viscosity, density, and
compressibility, influencing behavior in
response to forces, temperature, and
pressure.
Examples
Viscosity: Honey's slow pour illustrates
high viscosity, resisting flow due to
internal friction between its molecules.
Density: Ice floating on water
showcases lower density, as its mass
displaces less water compared to the
liquid state.
7. Buoyancy
Buoyancy is the upward force exerted
by a fluid, such as water,
counteracting the weight of an object,
allowing flotation.
8. Examples
Floating Boat: A boat stays afloat due to
buoyancy, as the water it displaces
generates an upward force supporting it.
Helium Balloon: A helium balloon rises
in the air because its buoyancy
surpasses its weight, defying gravity.
Charateristic of bouyancy forces
Buoyancy forces depend on displaced
fluid volume, acting upward, equal to the
weight of the fluid displaced, determining
an object's flotation.
9. Flotation
Flotation is the ability of an object to stay
afloat in a fluid, counteracting gravity
with buoyant forces.
Examples
Life Vest: A life vest provides flotation,
helping a person stay buoyant in water
by displacing enough water to support
them.
Inflatable Raft: An inflatable raft floats
on water, demonstrating flotation as the
buoyant force counteracts the weight of
the raft and occupants.
10. Drag
Drag is the resistance force opposing
motion through a fluid, like air or water,
affecting objects moving through the
medium.
Examples
Cycling: Cyclists experience air
resistance (drag) while riding,
influenced by factors like speed, body
position, and wind conditions.
Swimming: Swimmers encounter water
resistance (drag) as they move through
the water, impacting their speed and
energy efficiency.
11. Skin Friction
Skin friction is the resistance force generated
at the interface
between a fluid and a surface, influencing
fluid flow behavior.
Example
Aircraft Wing: Skin friction occurs between
the air and the surface of an aircraft wing,
affecting its aerodynamic performance.
Pipe Flow: Fluid flowing through a pipe
experiences skin friction along the pipe walls,
influencing the efficiency of fluid transport.
12. Form Drag
Form drag is the resistance force
caused by the shape of an object
moving through a fluid, such as air or
water.
Example
Car Design: Form drag is evident in
the aerodynamic shape of cars,
affecting fuel efficiency by minimizing
air resistance during motion.
13. Wave Drag
Wave drag results from the formation
of shock waves as an object
approaches the speed of sound,
creating additional aerodynamic
resistance.
Example
Supersonic Aircraft: As an aircraft
approaches and exceeds the speed of
sound, wave drag increases,
influencing its aerodynamic
performance and fuel efficiency.
14. Lift Force
Lift force is an upward force generated
by an airfoil or wing, counteracting
gravity and enabling aircraft or lift- based
motion.
Example
Airplane Flight: Lift force from wings
opposes gravity, allowing airplanes to
ascend and stay airborne during flight.
Kite Flying: Lift generated by the kite's
shape allows it to rise and remain aloft
when subjected to wind.
