ForceForce

What is Force?What is Force? Force is the action of Force is the action of

one body on the one body on the another body.another body.

oror

Force may be defined Force may be defined as an action which as an action which changes or tends to changes or tends to change the state of change the state of rest or of uniform rest or of uniform motion of body.motion of body.

Newton's second law of motionNewton's second law of motion

force = mass * acceleration force = mass * acceleration

= mass * length/( time )2 = mass * length/( time )2

The original form of Newton's second The original form of Newton's second law states that the net force acting law states that the net force acting upon an object is equal to the rate at upon an object is equal to the rate at which its momentum changes with which its momentum changes with time. time.

Effect of a ForceEffect of a Force 1. A force can change the motion of a 1. A force can change the motion of a

body. If a body is at rest, the force may set body. If a body is at rest, the force may set it into the motion and if the body is it into the motion and if the body is already in the motion, the force may already in the motion, the force may accelerate or retard it.accelerate or retard it.

2. It can bring the object in to rest by 2. 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 the 3. It can produce internal stresses in the body, on which it acts.body, on which it acts.

Types of Forces Types 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

1. Applied Force1. Applied Force A force that is applied A force that is applied

to an object by a to an object by a person or another person or another object. object.

If a person is pushing If a person is pushing a desk across the a desk across the room, then there is an room, then there is an applied force acting applied force acting upon the object. The upon the object. The applied force is the applied force is the force exerted on the force exerted on the desk by the person.desk by the person.

2. Gravity Force2. Gravity Force

The force of gravity The force of gravity is the force with is the force with which the earth, which the earth, moon, or other moon, or other massively large massively large object attracts object attracts another object another object towards itself. towards itself.

This is the weight This is the weight of the object. of the object.

3. Normal Force3. Normal Force The normal force is The normal force is

the support force the support force exerted upon an exerted upon an object that is in object that is in contact with another contact with another stable object. stable object.

If a person leans If a person leans against a wall, the against a wall, the wall pushes wall pushes horizontally on the horizontally on the person.person.

4. Friction Force4. Friction Force

The friction force is The friction force is the force exerted by a the force exerted by a surface as an object surface as an object moves across it or moves across it or makes an effort to makes an effort to move across it. move across it.

There are at least two There are at least two types of friction force - types of friction force - slidingsliding and and static static friction.friction.

5. Air Resistance Force5. Air Resistance Force The air resistance is a The air resistance is a

special type of frictional special type of frictional force that acts upon force that acts upon objects as they travel objects as they travel through the air. through the air.

The force of air resistance The force of air resistance is often observed to is often observed to oppose the motion of an oppose the motion of an object. object.

This force will frequently This force will frequently be neglected due to its be neglected due to its negligible magnitude negligible magnitude

6. Tension Force 6. Tension Force The tension force is the The tension force is the

force that is transmitted force that is transmitted through a string, rope, through a string, rope, cable or wire when it is cable or wire when it is pulled tight by forces pulled tight by forces acting from opposite ends. acting from opposite ends.

The tension force is The tension force is directed along the length directed along the length of the wire and pulls of the wire and pulls equally on the objects on equally on the objects on the opposite ends of the the opposite ends of the wire.wire.

7. Spring Force7. Spring Force The spring force is the The spring force is the

force exerted by a force exerted by a compressed or stretched compressed or stretched spring upon any object spring upon any object that is attached to it. that is attached to it.

An object that compresses An object that compresses or stretches a spring is or stretches a spring is always acted upon by a always acted upon by a force that restores the force that restores the object to its rest or object to its rest or equilibrium position. equilibrium position.

Force Systems Force Systems A force system is a collection of forces A force system is a collection of forces

acting on a body in one or more planes acting on a body in one or more planes

1. Collinear 1. Collinear 2. Concurrent2. Concurrent3. Co-planer 3. Co-planer 4. Coplanar Concurrent4. Coplanar Concurrent5. Non - Coplanar Concurrent 5. Non - Coplanar Concurrent 6. Coplanar non-concurrent6. Coplanar non-concurrent7. Non -coplanar non -concurrent7. Non -coplanar non -concurrent

1. Collinear -1. Collinear - The forces whose lines of action lie on the same line are known The 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 concurrent The 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 known The 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 their The 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 but The 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 but The forces, Which do not meet at one point but their line of action lie on the same plane, are known as coplanar non-concurrent their 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 point The forces, which do not meet at one point and their line of action do not lie on the same plane, are known as non -and their line of action do not lie on the same plane, are known as non -

coplanar non -concurrent forces. coplanar non -concurrent forces.

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A Power Point Presentation ByA Power Point Presentation By

Yogendra Singh ShekhawatYogendra Singh Shekhawat

B. Tech, Mechanical EngineeringB. Tech, Mechanical Engineering