Force is defined as an influence that causes an object to undergo a change in motion. There are two types of forces: contact forces, which require direct physical contact between objects, and action-at-a-distance forces like gravity and magnetism that do not require contact. Newton's second law states that the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. Forces can change the motion of objects by accelerating or retarding them, bring objects to rest, or produce internal stresses in objects. Common forces include applied, gravitational, normal, frictional, air resistance, tension

1. ForceForce

2. What is Force?What is Force?
 Force is the action ofForce is the action of
one body on theone body on the
another body.another body.
oror
Force may be definedForce may be defined
as an action whichas an action which
changes or tends tochanges or tends to
change the state ofchange the state of
rest or of uniformrest or of uniform
motion of body.motion of body.

3. Newton's second law of motionNewton's second law of motion
 force = mass * accelerationforce = mass * acceleration
= mass * length/( time )2= mass * length/( time )2
 The original form of Newton's secondThe original form of Newton's second
law states that the net force actinglaw states that the net force acting
upon an object is equal to the rate atupon an object is equal to the rate at
which its momentum changes withwhich its momentum changes with
time.time.

4. Effect of a ForceEffect of a Force
 1. A force can change the motion of a1. A force can change the motion of a
body. If a body is at rest, the force maybody. If a body is at rest, the force may
set it into the motion and if the body isset it into the motion and if the body is
already in the motion, the force mayalready in the motion, the force may
accelerate or retard it.accelerate or retard it.
 2. It can bring the object in to rest by2. It can bring the object in to rest by
retarding the motion of the object.retarding the motion of the object.
 3. It can produce internal stresses in the3. It can produce internal stresses in the
body, on which it acts.body, on which it acts.

5. Types of ForcesTypes of Forces
 1. Contact Forces -1. Contact Forces -
 (a) Frictional Force(a) Frictional Force
 (b) Tension Force(b) Tension Force
 (c) Normal Force(c) Normal Force
 (d) Air Resistance Force(d) Air Resistance Force
 (e) Applied Force(e) Applied Force
 (f) Spring Force(f) Spring Force
 2. Action-at-a-Distance Forces -2. Action-at-a-Distance Forces -
 (a) Gravitational Force(a) Gravitational Force
 (b) Electrical Force(b) Electrical Force
 (c) Magnetic Force(c) Magnetic Force

6. 1. Applied Force1. Applied Force
 A force that is appliedA force that is applied
to an object by ato an object by a
person or anotherperson or another
object.object.
 If a person is pushingIf a person is pushing
a desk across thea desk across the
room, then there is anroom, then there is an
applied force actingapplied force acting
upon the object. Theupon the object. The
applied force is theapplied force is the
force exerted on theforce exerted on the
desk by the person.desk by the person.

7. 2. Gravity Force2. Gravity Force
 The force of gravityThe force of gravity
is the force withis the force with
which the earth,which the earth,
moon, or othermoon, or other
massively largemassively large
object attractsobject attracts
another objectanother object
towards itself.towards itself.
 This is the weightThis is the weight
of the object.of the object.

8. 3. Normal Force3. Normal Force
 The normal force isThe normal force is
the support forcethe support force
exerted upon anexerted upon an
object that is inobject that is in
contact with anothercontact with another
stable object.stable object.
 If a person leansIf a person leans
against a wall, theagainst a wall, the
wall pusheswall pushes
horizontally on thehorizontally on the
person.person.

9. 4. Friction Force4. Friction Force
 The friction force isThe friction force is
the force exerted by athe force exerted by a
surface as an objectsurface as an object
moves across it ormoves across it or
makes an effort tomakes an effort to
move across it.move across it.
 There are at least twoThere are at least two
types of friction force -types of friction force -
slidingsliding andand staticstatic
friction.friction.

10. 5. Air Resistance Force5. Air Resistance Force
 The air resistance is aThe air resistance is a
special type of frictionalspecial type of frictional
force that acts uponforce that acts upon
objects as they travelobjects as they travel
through the air.through the air.
 The force of air resistanceThe force of air resistance
is often observed tois often observed to
oppose the motion of anoppose the motion of an
object.object.
 This force will frequentlyThis force will frequently
be neglected due to itsbe neglected due to its
negligible magnitudenegligible magnitude

11. 6. Tension Force6. Tension Force
 The tension force is theThe tension force is the
force that is transmittedforce that is transmitted
through a string, rope,through a string, rope,
cable or wire when it iscable or wire when it is
pulled tight by forcespulled tight by forces
acting from opposite ends.acting from opposite ends.
 The tension force isThe tension force is
directed along the lengthdirected along the length
of the wire and pullsof the wire and pulls
equally on the objects onequally on the objects on
the opposite ends of thethe opposite ends of the
wire.wire.

12. 7. Spring Force7. Spring Force
 The spring force is theThe spring force is the
force exerted by aforce exerted by a
compressed or stretchedcompressed or stretched
spring upon any objectspring upon any object
that is attached to it.that is attached to it.
 An object that compressesAn object that compresses
or stretches a spring isor stretches a spring is
always acted upon by aalways acted upon by a
force that restores theforce that restores the
object to its rest orobject to its rest or
equilibrium position.equilibrium position.

13. Force SystemsForce Systems
A force system is a collection of forcesA force system is a collection of forces
acting on a body in one or more planesacting on a body in one or more planes
1. Collinear1. Collinear
2. Concurrent2. Concurrent
3. Co-planer3. Co-planer
4. Coplanar Concurrent4. Coplanar Concurrent
5. Non - Coplanar Concurrent5. Non - Coplanar Concurrent
6. Coplanar non-concurrent6. Coplanar non-concurrent
7. Non -coplanar non -concurrent7. Non -coplanar non -concurrent

14. 1. Collinear -1. Collinear - The forces whose lines of action lie on the same line are knownThe forces whose lines of action lie on the same line are known
as collinear forces.as collinear forces.
2. Concurrent -2. Concurrent - The forces, which meet at one point, are known as concurrentThe forces, which meet at one point, are known as concurrent
forces. Concurrent forces may or may not be collinear.forces. Concurrent forces may or may not be collinear.
3. Co planer -3. Co planer - The forces whose line of action lie on the same plane, are knownThe forces whose line of action lie on the same plane, are known
as co planer forces.as co planer forces.
4. Coplanar Concurrent Forces -4. Coplanar Concurrent Forces - The forces, which meet at one point and theirThe forces, which meet at one point and their
lines of action lie on the same plane, are known as coplanar concurrent forces.lines of action lie on the same plane, are known as coplanar concurrent forces.
5. Non - Coplanar Concurrent Forces -5. Non - Coplanar Concurrent Forces - The forces, which meet at one point butThe forces, which meet at one point but
their lines of action do not lie on the same plane, are known as coplanar non-their lines of action do not lie on the same plane, are known as coplanar non-
concurrent forces.concurrent forces.
6. Coplanar non-concurrent -6. Coplanar non-concurrent - The forces, Which do not meet at one point butThe forces, Which do not meet at one point but
their line of action lie on the same plane, are known as coplanar non-concurrenttheir line of action lie on the same plane, are known as coplanar non-concurrent
forces.forces.
7. Non -coplanar non -concurrent -7. Non -coplanar non -concurrent - The forces, which do not meet at one pointThe forces, which do not meet at one point
and their line of action do not lie on the same plane, are known as nonand their line of action do not lie on the same plane, are known as non
-coplanar non -concurrent forces.-coplanar non -concurrent forces.

15. For more visitFor more visit
www.studyhubz.comwww.studyhubz.com
A Power Point Presentation ByA Power Point Presentation By
Yogendra Singh ShekhawatYogendra Singh Shekhawat
B. Tech, Mechanical EngineeringB. Tech, Mechanical Engineering