VIBRATIONS Sushil Kumar Outline...

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VIBRATIONS Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM Superposition Nature of Motion Energy of the System Examples VIBRATIONS Unit 1 Week 1 Sushil Kumar Singh SGTB Khalsa College University of Delhi www.sushilsingh.weebly.com July XX – August XX, 2010

Transcript of VIBRATIONS Sushil Kumar Outline...

Page 1: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

VIBRATIONSUnit 1 Week 1

Sushil Kumar Singh

SGTB Khalsa CollegeUniversity of Delhi

www.sushilsingh.weebly.com

July XX – August XX, 2010

Page 2: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

1 Simple Harmonic Motion

2 Linearity of EOM ⇒ Superposition

3 Nature of Motion

4 Energy of the System

5 Examples

Page 3: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Definition

The behaviour of displacement with time has a sinusoidal orcosinusoidal dependence.

The maximum displacement on either side of the equilibrium is thesame.

The energy is conserved and the oscillation continues forever.

Page 4: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Definition

The behaviour of displacement with time has a sinusoidal orcosinusoidal dependence.

The maximum displacement on either side of the equilibrium is thesame.

The energy is conserved and the oscillation continues forever.

Page 5: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Definition

The behaviour of displacement with time has a sinusoidal orcosinusoidal dependence.

The maximum displacement on either side of the equilibrium is thesame.

The energy is conserved and the oscillation continues forever.

Page 6: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Examples

a simple pendulum, a mass m swinging at the end of a light rigid rodof length l

a frictionless U-tube of constant cross-sectional area containing alength l of liquid, density ρ, oscillating about its equilibrium positionof equal levels in each limb

an electrical circuit, an inductance L connected across a capacitanceC carrying a charge q

Page 7: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Examples

a simple pendulum, a mass m swinging at the end of a light rigid rodof length l

a frictionless U-tube of constant cross-sectional area containing alength l of liquid, density ρ, oscillating about its equilibrium positionof equal levels in each limb

an electrical circuit, an inductance L connected across a capacitanceC carrying a charge q

Page 8: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Examples

a simple pendulum, a mass m swinging at the end of a light rigid rodof length l

a frictionless U-tube of constant cross-sectional area containing alength l of liquid, density ρ, oscillating about its equilibrium positionof equal levels in each limb

an electrical circuit, an inductance L connected across a capacitanceC carrying a charge q

Page 9: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Equation of Motion

A small displacement ~x from its equilibrium position sets up arestoring force which is proportional to x acting in a direction towardsthe equilibrium position.

Thus, this restoring force ~F may be written

~F = −k~x (1)

where k, the constant of proportionality, is called the stiffness and thenegative sign shows that the force is acting against the direction ofincreasing displacement and back towards the equilibrium position.This is Hooke’s Law of Elasticity.

If the stiffness k is constant, then the restoring force F when plottedversus x , will produce a straight line and the system is said to belinear.

The equation of motion of such a disturbed system is given by thedynamic balance between the forces acting on the system, which byNewton’s Law is

m~x = −k~x (2)

Page 10: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Equation of Motion

A small displacement ~x from its equilibrium position sets up arestoring force which is proportional to x acting in a direction towardsthe equilibrium position.

Thus, this restoring force ~F may be written

~F = −k~x (1)

where k, the constant of proportionality, is called the stiffness and thenegative sign shows that the force is acting against the direction ofincreasing displacement and back towards the equilibrium position.This is Hooke’s Law of Elasticity.

If the stiffness k is constant, then the restoring force F when plottedversus x , will produce a straight line and the system is said to belinear.

The equation of motion of such a disturbed system is given by thedynamic balance between the forces acting on the system, which byNewton’s Law is

m~x = −k~x (2)

Page 11: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Equation of Motion

A small displacement ~x from its equilibrium position sets up arestoring force which is proportional to x acting in a direction towardsthe equilibrium position.

Thus, this restoring force ~F may be written

~F = −k~x (1)

where k, the constant of proportionality, is called the stiffness and thenegative sign shows that the force is acting against the direction ofincreasing displacement and back towards the equilibrium position.This is Hooke’s Law of Elasticity.

If the stiffness k is constant, then the restoring force F when plottedversus x , will produce a straight line and the system is said to belinear.

The equation of motion of such a disturbed system is given by thedynamic balance between the forces acting on the system, which byNewton’s Law is

m~x = −k~x (2)

Page 12: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Equation of Motion

A small displacement ~x from its equilibrium position sets up arestoring force which is proportional to x acting in a direction towardsthe equilibrium position.

Thus, this restoring force ~F may be written

~F = −k~x (1)

where k, the constant of proportionality, is called the stiffness and thenegative sign shows that the force is acting against the direction ofincreasing displacement and back towards the equilibrium position.This is Hooke’s Law of Elasticity.

If the stiffness k is constant, then the restoring force F when plottedversus x , will produce a straight line and the system is said to belinear.

The equation of motion of such a disturbed system is given by thedynamic balance between the forces acting on the system, which byNewton’s Law is

m~x = −k~x (2)

Page 13: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The equation being linear we find that if X1 and X2 are two differentsolutions then

m ~X1 = −k ~X1

m ~X2 = −k ~X2

m ~X1 + m ~X2 = (−k ~X1) + (−k ~X2)

md2(~X1 + ~X2)

dt2= −k(~X1 + ~X2)

Page 14: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The equation being linear we find that if X1 and X2 are two differentsolutions then

m ~X1 = −k ~X1

m ~X2 = −k ~X2

m ~X1 + m ~X2 = (−k ~X1) + (−k ~X2)

md2(~X1 + ~X2)

dt2= −k(~X1 + ~X2)

Page 15: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The equation being linear we find that if X1 and X2 are two differentsolutions then

m ~X1 = −k ~X1

m ~X2 = −k ~X2

m ~X1 + m ~X2 = (−k ~X1) + (−k ~X2)

md2(~X1 + ~X2)

dt2= −k(~X1 + ~X2)

Page 16: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The equation being linear we find that if X1 and X2 are two differentsolutions then

m ~X1 = −k ~X1

m ~X2 = −k ~X2

m ~X1 + m ~X2 = (−k ~X1) + (−k ~X2)

md2(~X1 + ~X2)

dt2= −k(~X1 + ~X2)

Page 17: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The equation being linear we find that if X1 and X2 are two differentsolutions then

m ~X1 = −k ~X1

m ~X2 = −k ~X2

m ~X1 + m ~X2 = (−k ~X1) + (−k ~X2)

md2(~X1 + ~X2)

dt2= −k(~X1 + ~X2)

Page 18: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

General Solution

We find thatx = A cosωt

andx = B sinωt

are independent solutions with

ω =

√k

m

The complete or general solution is given by the superposition of bothvalues for x so we have

x = A cosωt + B sinωt

If we rewrite the constants as A = a sinφ and B = a cosφ where φ isa constant angle, then a =

√A2 + B2 and

x = a sinφ cosωt + a cosφ sinωt = a sin(ωt + φ) (3)

Page 19: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

General Solution

We find thatx = A cosωt

andx = B sinωt

are independent solutions with

ω =

√k

m

The complete or general solution is given by the superposition of bothvalues for x so we have

x = A cosωt + B sinωt

If we rewrite the constants as A = a sinφ and B = a cosφ where φ isa constant angle, then a =

√A2 + B2 and

x = a sinφ cosωt + a cosφ sinωt = a sin(ωt + φ) (3)

Page 20: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

General Solution

We find thatx = A cosωt

andx = B sinωt

are independent solutions with

ω =

√k

m

The complete or general solution is given by the superposition of bothvalues for x so we have

x = A cosωt + B sinωt

If we rewrite the constants as A = a sinφ and B = a cosφ where φ isa constant angle, then a =

√A2 + B2 and

x = a sinφ cosωt + a cosφ sinωt = a sin(ωt + φ) (3)

Page 21: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Features

The system will oscillate with Time Period T = 2π/ω between thevalues of x = ±a so that a is the Amplitude of displacement.

The magnitude of a is determined by the total energy of theoscillator.

The angle φ is called the Phase constant. The inclusion of φ in thesolution allows the motion to be defined from any starting point.

The velocity of the oscillating system is

x = ωa cos(ωt + φ) = ωa sin(ωt + φ+ π/2)

while the acceleration is

x = −ω2a sin(ωt + φ) = ω2a sin(ωt + φ+ π)

Page 22: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Features

The system will oscillate with Time Period T = 2π/ω between thevalues of x = ±a so that a is the Amplitude of displacement.

The magnitude of a is determined by the total energy of theoscillator.

The angle φ is called the Phase constant. The inclusion of φ in thesolution allows the motion to be defined from any starting point.

The velocity of the oscillating system is

x = ωa cos(ωt + φ) = ωa sin(ωt + φ+ π/2)

while the acceleration is

x = −ω2a sin(ωt + φ) = ω2a sin(ωt + φ+ π)

Page 23: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Features

The system will oscillate with Time Period T = 2π/ω between thevalues of x = ±a so that a is the Amplitude of displacement.

The magnitude of a is determined by the total energy of theoscillator.

The angle φ is called the Phase constant. The inclusion of φ in thesolution allows the motion to be defined from any starting point.

The velocity of the oscillating system is

x = ωa cos(ωt + φ) = ωa sin(ωt + φ+ π/2)

while the acceleration is

x = −ω2a sin(ωt + φ) = ω2a sin(ωt + φ+ π)

Page 24: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Features

The system will oscillate with Time Period T = 2π/ω between thevalues of x = ±a so that a is the Amplitude of displacement.

The magnitude of a is determined by the total energy of theoscillator.

The angle φ is called the Phase constant. The inclusion of φ in thesolution allows the motion to be defined from any starting point.

The velocity of the oscillating system is

x = ωa cos(ωt + φ) = ωa sin(ωt + φ+ π/2)

while the acceleration is

x = −ω2a sin(ωt + φ) = ω2a sin(ωt + φ+ π)

Page 25: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Derivation

The fact that the velocity is zero at maximum displacement in simpleharmonic motion and is a maximum at zero displacement illustratesthe important concept of an exchange between kinetic and potentialenergy.

The potential energy at a position x is found by summing all thesmall elements of work done by the system against the restoring forceover the range zero to x where x = 0 gives zero potential energy

U =

∫−(−k~x) · d~x =

∫ x

0

kxdx =1

2kx2

The kinetic energy at that postion x is

K =1

2mx2

The total energy at any position x

E = U + K =1

2kx2 +

1

2mx2 =

1

2ka2 (4)

Page 26: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Derivation

The fact that the velocity is zero at maximum displacement in simpleharmonic motion and is a maximum at zero displacement illustratesthe important concept of an exchange between kinetic and potentialenergy.

The potential energy at a position x is found by summing all thesmall elements of work done by the system against the restoring forceover the range zero to x where x = 0 gives zero potential energy

U =

∫−(−k~x) · d~x =

∫ x

0

kxdx =1

2kx2

The kinetic energy at that postion x is

K =1

2mx2

The total energy at any position x

E = U + K =1

2kx2 +

1

2mx2 =

1

2ka2 (4)

Page 27: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Derivation

The fact that the velocity is zero at maximum displacement in simpleharmonic motion and is a maximum at zero displacement illustratesthe important concept of an exchange between kinetic and potentialenergy.

The potential energy at a position x is found by summing all thesmall elements of work done by the system against the restoring forceover the range zero to x where x = 0 gives zero potential energy

U =

∫−(−k~x) · d~x =

∫ x

0

kxdx =1

2kx2

The kinetic energy at that postion x is

K =1

2mx2

The total energy at any position x

E = U + K =1

2kx2 +

1

2mx2 =

1

2ka2 (4)

Page 28: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Derivation

The fact that the velocity is zero at maximum displacement in simpleharmonic motion and is a maximum at zero displacement illustratesthe important concept of an exchange between kinetic and potentialenergy.

The potential energy at a position x is found by summing all thesmall elements of work done by the system against the restoring forceover the range zero to x where x = 0 gives zero potential energy

U =

∫−(−k~x) · d~x =

∫ x

0

kxdx =1

2kx2

The kinetic energy at that postion x is

K =1

2mx2

The total energy at any position x

E = U + K =1

2kx2 +

1

2mx2 =

1

2ka2 (4)

Page 29: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The maximum potential energy is Umax = 12ka2

The maximum kinetic energy is Kmax = 12mx2 = 1

2mω2a2 = 1

2ka2

The average kinetic energy 〈K〉 and the average potential energy 〈U〉over a time period T

〈K〉 =

∮T

12mx2dt∮T dt

=

∫T

12mω2a2 cos2(ωt + φ)dt

T

=

∫T

12mω2a2 cos2 θdθ

ωT

=1

2mω2a2

∫T cos2 θdθ

=1

2ka2

(4∫ π/20 cos2 θdθ)

=1

4ka2 =

1

2E

〈U〉 =

∮T

12kx2dt∮

T dt

=

∫T

12ka2 sin2(ωt + φ)dt

T

=

∫T

12ka2 sin2 θdθ

ωT

=1

2ka2

∫T sin2 θdθ

=1

2ka2

(4∫ π/20 sin2 θdθ)

=1

4ka2 =

1

2E

Page 30: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The maximum potential energy is Umax = 12ka2

The maximum kinetic energy is Kmax = 12mx2 = 1

2mω2a2 = 1

2ka2

The average kinetic energy 〈K〉 and the average potential energy 〈U〉over a time period T

〈K〉 =

∮T

12mx2dt∮T dt

=

∫T

12mω2a2 cos2(ωt + φ)dt

T

=

∫T

12mω2a2 cos2 θdθ

ωT

=1

2mω2a2

∫T cos2 θdθ

=1

2ka2

(4∫ π/20 cos2 θdθ)

=1

4ka2 =

1

2E

〈U〉 =

∮T

12kx2dt∮

T dt

=

∫T

12ka2 sin2(ωt + φ)dt

T

=

∫T

12ka2 sin2 θdθ

ωT

=1

2ka2

∫T sin2 θdθ

=1

2ka2

(4∫ π/20 sin2 θdθ)

=1

4ka2 =

1

2E

Page 31: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The maximum potential energy is Umax = 12ka2

The maximum kinetic energy is Kmax = 12mx2 = 1

2mω2a2 = 1

2ka2

The average kinetic energy 〈K〉 and the average potential energy 〈U〉over a time period T

〈K〉 =

∮T

12mx2dt∮T dt

=

∫T

12mω2a2 cos2(ωt + φ)dt

T

=

∫T

12mω2a2 cos2 θdθ

ωT

=1

2mω2a2

∫T cos2 θdθ

=1

2ka2

(4∫ π/20 cos2 θdθ)

=1

4ka2 =

1

2E

〈U〉 =

∮T

12kx2dt∮

T dt

=

∫T

12ka2 sin2(ωt + φ)dt

T

=

∫T

12ka2 sin2 θdθ

ωT

=1

2ka2

∫T sin2 θdθ

=1

2ka2

(4∫ π/20 sin2 θdθ)

=1

4ka2 =

1

2E

Page 32: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The maximum potential energy is Umax = 12ka2

The maximum kinetic energy is Kmax = 12mx2 = 1

2mω2a2 = 1

2ka2

The average kinetic energy 〈K〉 and the average potential energy 〈U〉over a time period T

〈K〉 =

∮T

12mx2dt∮T dt

=

∫T

12mω2a2 cos2(ωt + φ)dt

T

=

∫T

12mω2a2 cos2 θdθ

ωT

=1

2mω2a2

∫T cos2 θdθ

=1

2ka2

(4∫ π/20 cos2 θdθ)

=1

4ka2 =

1

2E

〈U〉 =

∮T

12kx2dt∮

T dt

=

∫T

12ka2 sin2(ωt + φ)dt

T

=

∫T

12ka2 sin2 θdθ

ωT

=1

2ka2

∫T sin2 θdθ

=1

2ka2

(4∫ π/20 sin2 θdθ)

=1

4ka2 =

1

2E

Page 33: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Ideas

The maximum potential energy is Umax = 12ka2

The maximum kinetic energy is Kmax = 12mx2 = 1

2mω2a2 = 1

2ka2

The average kinetic energy 〈K〉 and the average potential energy 〈U〉over a time period T

〈K〉 =

∮T

12mx2dt∮T dt

=

∫T

12mω2a2 cos2(ωt + φ)dt

T

=

∫T

12mω2a2 cos2 θdθ

ωT

=1

2mω2a2

∫T cos2 θdθ

=1

2ka2

(4∫ π/20 cos2 θdθ)

=1

4ka2 =

1

2E

〈U〉 =

∮T

12kx2dt∮

T dt

=

∫T

12ka2 sin2(ωt + φ)dt

T

=

∫T

12ka2 sin2 θdθ

ωT

=1

2ka2

∫T sin2 θdθ

=1

2ka2

(4∫ π/20 sin2 θdθ)

=1

4ka2 =

1

2E

Page 34: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Setting up EOM

a simple pendulum (ml2)~θ = ~τ =~l × ~F = lmg sin θ(−θ) withω2 = g/l

a frictionless U-tube (lAρ)x = −[(2x)Aρ]g with ω2 = 2g/l

an LC circuit VL(= −Ldi/dt = −Ld2q/dt2) = VC (= q/C) withω2 = 1/LC

Page 35: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Setting up EOM

a simple pendulum (ml2)~θ = ~τ =~l × ~F = lmg sin θ(−θ) withω2 = g/l

a frictionless U-tube (lAρ)x = −[(2x)Aρ]g with ω2 = 2g/l

an LC circuit VL(= −Ldi/dt = −Ld2q/dt2) = VC (= q/C) withω2 = 1/LC

Page 36: VIBRATIONS Sushil Kumar Outline VIBRATIONSsushilsingh.weebly.com/uploads/2/5/5/4/2554946/viblecu1w1.pdf · Sushil Kumar Singh Outline Simple Harmonic Motion Linearity of EOM) Superposition

VIBRATIONS

Sushil KumarSingh

Outline

Simple HarmonicMotion

Linearity of EOM⇒ Superposition

Nature of Motion

Energy of theSystem

Examples

Setting up EOM

a simple pendulum (ml2)~θ = ~τ =~l × ~F = lmg sin θ(−θ) withω2 = g/l

a frictionless U-tube (lAρ)x = −[(2x)Aρ]g with ω2 = 2g/l

an LC circuit VL(= −Ldi/dt = −Ld2q/dt2) = VC (= q/C) withω2 = 1/LC