This PPT will help with basic information about Sports Biomechanics.

1. Vinod Baitha

2. Force
⚫A push orpull thatoneobjectexerts on anotherobject.
⚫Examples: Earth (pulls usdownward), chairs, pencils.
⚫Example: pulling a draweropen; you exert forceon the
drawer.

3. • An object’s motion changes in response to a
force.
• Aforce has a size and a direction—both are
important in determining an object’s motion.
• The force you exert on the book when you
push is called a contact force.
• Acontact force is a force that is exerted when
two objects are touching each other.

4. Long-Range Forces
• A forcecan beexerted if two objects are not
in contact.
• If you bring a magnetclose to a paperclip,
the paperclip moves toward the magnet, so
a force must beacting on the paperclip.

5. Long-Range Forces
• A dropped ball will fall downward, even
though nothing appears to be touching it.
• The forcesacting on the paperclipand the ball
are long-range forces.
• In SI units the unit of force is the Newton,
which is abbreviated N and named for Isaac
Newton.
• One Newton is about theamountof force needed
to lifta half cupof water.

6. Speed and Velocity
⚫Speed is how fast an object is
moving without regard to direction.
⚫Speed is a scalar quantity like distance.
⚫Speed (s) is defined as the rate of
change of distance (s = l/t), so typical units
are m/s, ft/s, km/hr, or miles/hr.

7. Speed
Forexample, 30 miles per hour means object travelsdistance
of 30 miles in an elapsed timeof one hour. Write as,
(SPEED) =
Speed isone way to describe motion. It describes how fastan
object is moving using distance and time. Average speed is
the total distance traveled over the total time and
instantaneous speed is thespeed at a particular moment
(Distance traveled)
(Time elapsed)
30 miles per hour = 30
miles
hour

8. Practice:
What is the average speed of a cheetah that
sprints 100 meters in 14 seconds? How about
if it sprints 50 meters in 10 seconds?
A car has an average speed of 100 kilometers per
hour. How fardoes it travel in 30 minutes?

9. Velocity
• Constantspeed means steadyspeed. Something
with constantspeed doesn’tspeed uporslowdown.
• Constantvelocity means both constantspeed and
constantdirection.
• Constant direction is a straight line, so constant
velocity means motion in a straight line atconstant
speed.
• Constant speed and constant velocityare not the same.
• A body may move at constant speed along acurved path
but it does not move with constant velocity, because its
direction ischanging every instant.

10. Practice
The speedometerof acar moving east
reads 100 km/h. It passes another car
moving west at 100 km/h. Do they have
same speed? Velocity?
During a certain period of time, the
speedometerof a carreads aconstant
60 km/h. Does this indicate a constant
speed? Constant velocity?

11. Velocity
⚫Velocity is the vector corresponding to
speed.
⚫V is the speed of an object, in a particular
direction.
⚫Velocity is the rate of change of
displacement (V = d/t), so its units are
the same as speed, and are usually
qualified by a directional adjective (i.e.,
horizontal, vertical, ).

12. Velocity
important because velocity defines
⚫The phrase “rate of change” is very
how
quickly position is changing in the specified
direction (displacement).

13. Scalar
⚫Scalars are quantities that are fully
described by a magnitude (or numerical
value) alone.
⚫Vectors are quantities that are fully
described by both a magnitude and a
direction.

14. Distance and displacement
Motion is change in position with respect to
some frame of reference. (final position
minus initial position). The simplest linear
motion variable is a scalar called Distance
(l).
(l) Is the length an object travelled
irrespective of direction (mtr, feet etc)

15. displacement
⚫displacement is a vector quantity.
⚫shows distance and direction of objects.
⚫Shortest distance from the reference
point.
⚫Displacements are calculated as
final position minus initial position in
that particular direction

16. Acceleration
Define acceleration as how fast velocity changes
Acceleration is a rate of a rate (units will have 2 timevalues)
(Change in Velocity)
(ACCELERATION) =
(Time interval)
Note:An object accelerates anytime its velocity changes.
Examples include:
Object speeds up.
Object slows down
Object changes direction (curved path)
Best example of acceleration is objects in free fall

17. Equations
⚫s = d/t
⚫v = d/t
⚫a = Δv/Δt
⚫g = 9.8 m/s/s

18. Inertia
Inertia:
⚫ Resistance to being
accelerated
Mass:
⚫ Quantityof matteran object
is madeof.
⚫ measureof the inertiaof the
object
⚫ scalarquantity
⚫ not thesameasweight

19. Mass
⚫Quantityof matteran object is madeof.
⚫measureof the inertiaof theobject
⚫scalarquantity
⚫not thesameas weight
⚫Massand Inertia
large mass=lotsof inertia
small mass=not lotsof inertia

20. rpoles
Weight
⚫ Weight (W) is the attractive force
between the earth and any body in
contact with it or close to its
surface
⚫ Product of the mass (m) of the
body and the acceleration caused
by the attractive force between it
and the earth
(g = 9.81 m·s-2)
i.e. W = m × g
⚫ Gravity is based on:
⚫ Mass of bodies
⚫ Distance between bodies
requator
r=radius of earth
r > r
equator poles
Gequator < gpoles
Wequator < Wpoles

21. ⚫Momentum:-
Is a commonly used term in sports. A
team that has the momentum is on the move and is
going to take someeffort tostop. A team that has a lot
of momentum is really on the move and is going to be
hard to stop. Momentum isa physics term; it refers to
thequantityof motion thatan object has. A sports
team that is on the move has the momentum. If an
object is in motion (on the move) then it has
momentum

22. ⚫Momentumcan bedefined as "mass in motion.“
⚫ All objects have mass; so if an object is moving, then it
has momentum - it has its mass in motion. The
amountof momentum thatan object has is dependent
upon twovariables: how much stuff is moving and
how fast the stuff is moving. Momentum depends
upon the variables mass and velocity. In terms of an
equation, the momentum of an object is equal to the
massof theobject times thevelocityof theobject.
⚫Momentum = mass • velocity

23. ⚫p = m • v
⚫where m is the massand
v is thevelocity.
The equation illustrates that
momentum isdirectly proportional toan object's mass
and directly proportional to theobject'svelocity.
⚫ The standard metric unitof momentum is the kg•m/s.

24. It is going to take more force to movea large
mass. Ten pounds is twiceas much as five pounds. It
will take twice as much force to move 10 pounds as it
will to move five pounds. When enough force is
applied to move either 10 pounds or five pounds and
they were both given the same speed of movement
(velocity), the 10-pound weight would have twice as
much momentum. Rememberthat momentum is not
justvelocity. While momentum is movement, it is
made upof bothvelocityand mass.

25. For example, it would take more effort (force) on your
part to catch the 10-pound weight (twice as much
effort) as it would for the five-pound weight if both
traveling at the same speed (velocity).

26. Types of momentum
⚫Linear
⚫Angular
⚫Linear momentum:-
Momentum is the quantity of motion
of a body in linear motion. It is equal to the product of
the body’s massand velocity.

27. That is :
momentum = Mass X velocity
M = m X v
where : m is the mass [Kg]
v is thevelocity[m/s]
M is the momentum[Kg m/s]

28. ⚫ Angular Momentum:-
Thequantityof angular motion
possessed bya body is called it’s Angular momentum.
justas linear momentumvaries with
avarying body massand varying velocity.

29. Angular momentum =
momentof inertia X Angularvelocity
H = j X ω
where :
j is the moment[Kg.m²]
ω is theangularvelocity[°/sorrad/s]
H is the angular momentum
[Kg.m².°/s or Kg.m².rad/s]

30. Impulse Defined
Impulse is defined as the product force acting on an
object and the time during which the force acts. The
symbol for impulse is J. So, by definition:
J = F t
Example: A50 N force is applied to a 100 kg boulder
for 3 s. The impulse of this force is J = (50 N) (3 s)
= 150 N·s.
Note that we didn’t need to know the mass of the
object in the above example.

31. Impulse Units
J = Ft shows why the SI unit for impulse is the Newton · second.
There is no special name for this unit, but it is equivalent to a kg·m/s.
proof: 1 N·s = 1 (kg·m/s2) (s) = 1 kg·m/s
Fnet = ma shows this is
equivalent to a newton.
Therefore, impulse and momentum have the same units, which leads
to a useful theorem.