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2. Contact force Non Contact forces
Frictional Force Gravitational Force
Tension Force Electrical Force
Normal Force Magnetic Force
Air Resistance Force
Applied Force
Spring Force

3. 1. contact forces
Contact forces are those forces that cause a change in another object because the
objects are physically touching one another, according to Reference.com.Examples of
contact forces include applied force, tension force, air resistance force and normal
force.
In order for force to exist, interaction between two objects must take place. The
interaction is sometimes as simple as one object sitting upon a surface. This is a type
of contact force because the two objects are touching, and the surface exerts force on
the object to support its weight. Contact force is one of the two general categories
into which forces between two objects are defined. The other is force from a
distance. Examples of this type of force are magnetic and gravitational
Image 1.

4. 2. Non Contact Force
Non Contact force is a force at a distance such as gravitational force, magnetic force
etc. It occurs between objects not touching each other like frictional force between
the snow and skis of a down hill skier. If the sum of the forces equals zero the object
remains in motion with same velocity in same direction. In other words if the object
is moving with same velocity in the same direction.
Before seeing about non contact force will see what is Gravity?
Its a imaginary force pulling everything towards the point where it has its field. All
the objects are pulled towards the earth without any physical contact with the
objects and bodies. These are non contact forces in the most basic sense.
It can be defined as:
Forces acting on any body without any physical contact between them.
(or)
When a force is applied on some body by another object without any
interaction or contact is called non contact force.

5. Image for non contact force
Image 2.

6. APPLIED FORCE3.
Force is a vector quantity. Vector is a physical quantity described by
magnitude (meaning the strength of the force) and direction. Applied force
means the force with which an object has been pushed or pulled by another
object. In physics, objects include atoms, planets, people, comets, machines,
machine parts and many other objects.
The force with which a comet hits another comet is an applied force. When
you ride your bike, you apply force to the bike's pedals, which pulls the chain,
which in turn moves the bike's wheel. When you mould a piece of modelling
clay, you apply the force of your hand to change the shape of the clay. Actions
like cracking an egg, throwing a ball, moving furniture or pushing a button
also involve applied force.

7. Image of applied
force
Image 3.

8. 4. Gravitational force
Gravitation is a force of attraction between all objects in the
universe. All objects in the universe are affected by the forces of
gravitation. The larger the object is, the stronger its force of
gravitation. On Earth, the largest object is the Earth itself, so all
objects are attracted or pulled down towards it. In our example, the
ball stays on the ground because of the gravitational force of Earth.
Example of Gravitational force
Gravity, unlike electromagnetism, is always attractive, and unlike the strong force, it
works over long distances. This makes it the most easily observed force on the largest
scales of the universe. The legendary insight of Isaac Newton was that this same force
is responsible for holding the moon in orbit around Earth, as well as keeping the
planets in their courses around the sun.

9. Image for Gravitational force
Image 4.

10. 5. Frictional force
Frictional forces are affected by the texture of the surfaces and the amount of
force pushing them together. The angle and position of the objects affects the
amount of frictional force. If an object is sitting flat against an object, then the
frictional force is equal to the object's weight. If the object is pushed against the
surface, the frictional force is increased and becomes greater than the object's
weight. Objects pulled away from the surface and those at an incline with the
surface have less frictional resistance.
Image 5.

11. Example of Frictional force
Friction most commonly refers to the resisting force generated when two solid
surfaces slide against one another. However, there is actually a wide variety of
different types of friction that includes skin friction, fluid friction, internal
friction, lubricated friction and dry friction. Each of these frictional energies has
unique features and dynamics, but the overarching hallmarks of frictional forces
remain the same.
When two touching surfaces slide against one another, complex interactions occur
at an electromagnetic level between the surface's charged particles. These
frictional forces convert the kinetic energy generated by their movements into
heat. These same principles apply to objects moving through a liquid or through
the air, creating different types of frictional energy. A frictional coefficient is
computed by determining the ratio of the force of friction between two objects and
the force that is pushing them together. Different combinations of surfaces have
different frictional coefficients. The shape of an object does not influence fiction;
the object's weight and the amount of force applied are the two affecting factors

12. 6. magnetic force
The technical definition of magnetic force is the mechanical force exerted
from a magnetic field to a magnetic pole that is placed within that particular
magnetic field. Magnetic force involves the simultaneous attraction and
repulsion that occurs between particles that are electrically charged and are
within the magnetic field itself.
A prime example of a magnetic field is the manner in which iron reacts
when placed in proximity to a magnet. Magnetic force is the primary reason
why electric engines are able to function; these engines contain rotating coils
of wire that are driven by magnetic force exerted by a magnetic field on an
electric current.
Example of Magnetic force

13. Image for magnetic force
Image 6.

14. 7. Muscular force
Muscular strength is an aspect of physical fitness that is typically gauged with the
maximum amount of weight that a given muscle can move for one repetition.
Muscular strength is increased by performing progressive resistance training over
time to improve the endurance of the muscle. Increased muscle strength can only be
achieved by working the muscle beyond its normal operation in order to break the
muscle tissue down in preparation for it to rebuild. As the muscle tires, small tears
occur within the muscle fibers. As these tears heal, the muscle becomes stronger. This
can be achieved by increasing the number of repetitions, the amount of weight and by
shortening times between strength training sessions. Building muscle strength takes
time. People looking to put on muscle should never push to lift more weight than the
muscle is ready for as injury may likely occur.
The initial benefit of increasing muscle strength is that it improves performance and
physical fitness. Other benefits include improved joint health, cardiovascular
endurance, flexibility, increased bone density, and a leaner physique with lower body
fat, among many others.

15. Example of muscular force
Image 7.

16. 8. Electrostatic force
Electrostatic force, which is also called the Coulomb force or Coulomb interaction, is
defined as the attraction or repulsion of different particles and materials based on
their electrical charges. Electrostatic force is one of the most basic forms of forces
used in the physical sciences, and was discovered by a French physicist named
Charles- Augustine de Coulomb in the 1700s. Coulomb discovered electrostatic force
after undertaking an experiment, and used the concept of electrostatic force to
describe the interaction of particles and molecules in a given space.
The interaction of molecules in an area is often complex, and depends on a number of
factors. While their movement, speed, shape and size are explained through other
terms in chemistry and physics, the interactions of these particles based on electrical
charge is described with electrostatic force. For electrostatic force to exist, two or
more molecules must be present. Most particles contain either positive or negative
electrical charges, and the type of charge that they possess plays a key role in
determining their likelihood of attracting or repelling each other. In larger objects,
other forces such as nuclear force, magnetic force, and gravity shape interactions as
well. Nuclear force may create strong bonds between atoms, while gravity and
magnetic forces pull objects together across long distances.

17. Image for Electrostatic force
Image 8.

19. Instructional Objectives
 Distinguish the Difference Between Static & Kinetic
Friction
 Solve Problems Involving Friction Effects

20.  Force that acts oppose
the relative motion of
two surfaces
 High for dry and rough
surfaces
 Low for smooth and
wet surfaces

21. Normal
Force FN
Friction
Force ff
Applied
Force F
Gravity
Force Fg
Fg = mg
FN = Fg
ff = F

22. Static Friction
frictionstaticoftcoefficien
Ff
s
sNs




FN
fs
F
Fg
The Force of Static
Friction keeps a
stationary object at
rest!

23. Kinetic Friction
frictionkineticoftcoefficien
Ff
k
kNk




FN
fk
F
Fg
Once the Force of Static
Friction is overcome, the
Force of Kinetic Friction
is what slows down a
moving object!
Motion

24. Types of Friction
I better be
safe Ump!!
To initiate motion of the box the
man must overcome the Force of
Static Friction
Upon sliding, the baseball player
will come to a complete stop due
to the Force of Kinetic Friction

25. Material Coefficient of
Static Friction S
Coefficient of
Kinetic Friction S
Rubber on Glass 2.0+ 2.0
Rubber on Concrete 1.0 0.8
Steel on Steel 0.74 0.57
Wood on Wood 0.25 – 0.5 0.2
Metal on Metal 0.15 0.06
Ice on Ice 0.1 0.03
Synovial Joints in
Humans
0.01 0.003

26. Static VS. Kinetic Friction

27. Static Friction Lab Procedure
• Connect the force detector to a block of wood
• Pull gently on the force sensor unit the block begins
to move
• Move the block slowly with constant force

28. Ideal Result

29. Kinetic Friction Lab Procedure
• Line up the block with the motion detector
• Push the block gently toward the motion detector so
that it comes to a stop approximately 1 foot away
from it
• From the velocity curve determine the deceleration
of the block
• Calculate the Force of Kinetic Friction
• Determine the coefficient of Kinetic Friction
Wooden block
Push

30. Application Analysis
 An empty cart is being
rolled across a
warehouse floor. If the
cart was filled, the
force of kinetic friction
between the cart and
the floor would
1. Decrease
2. Increase
3. Remain the same

31. Application Analysis
 Sand is often placed on an
icy road because the sand:
1. Decreases the coefficient of
friction between the tires
of a car and the road
2. Increases the coefficient of
friction between the tires
of a car and the road
3. Decrease the gravitational
force on a car
4. Increases the normal force
of a car on the road