Course Content
Class 11 Physics Chapter 4 Motion In A Plane
4 Motion in a plane 4.1 Introduction 4.2 Scalars and vectors 4.3 Multiplication of vectors by real numbers 4.4 Addition and subtraction of vectors – graphical method 4.5 Resolution of vectors 4.6 Vector addition – analytical method 4.7 Motion in a plane 4.8 Motion in a plane with constant acceleration 4.9 Relative velocity in two dimensions 4.10 Projectile motion 4.11 Uniform circular motion
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Class 11 Physics Chapter 5 Laws of motion
Section Name Topic Name 5 Laws of motion 5.1 Introduction 5.2 Aristotle’s fallacy 5.3 The law of inertia 5.4 Newton’s first law of motion 5.5 Newton’s second law of motion 5.6 Newton’s third law of motion 5.7 Conservation of momentum 5.8 Equilibrium of a particle 5.9 Common forces in mechanics 5.10 Circular motion 5.11 Solving problems in mechanics
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Class 11 Physics Chapter 6 Work Energy and Power
Section Name Topic Name 6 Work Energy and power 6.1 Introduction 6.2 Notions of work and kinetic energy : The work-energy theorem 6.3 Work 6.4 Kinetic energy 6.5 Work done by a variable force 6.6 The work-energy theorem for a variable force 6.7 The concept of potential energy 6.8 The conservation of mechanical energy 6.9 The potential energy of a spring 6.10 Various forms of energy : the law of conservation of energy 6.11 Power 6.12 Collisions
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Class 11 Physics Chapter 7 Rotation motion
Topics Introduction Centre of mass Motion of COM Linear Momentum of System of Particles Vector Product Angular velocity Torque & Angular Momentum Conservation of Angular Momentum Equilibrium of Rigid Body Centre of Gravity Moment of Inertia Theorem of perpendicular axis Theorem of parallel axis Moment of Inertia of Objects Kinematics of Rotational Motion about a Fixed Axis Dynamics of Rotational Motion about a Fixed Axis Angular Momentum In Case of Rotation about a Fixed Axis Rolling motion
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Class 11 Physics Chapter 9 mechanics properties of solid
Section Name Topic Name 9 Mechanical Properties Of Solids 9.1 Introduction 9.2 Elastic behaviour of solids 9.3 Stress and strain 9.4 Hooke’s law 9.5 Stress-strain curve 9.6 Elastic moduli 9.7 Applications of elastic behaviour of materials
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Class 11 Physics Chapter 11 Thermal Properties of matter
Section Name Topic Name 11 Thermal Properties of matter 11.1 Introduction 11.2 Temperature and heat 11.3 Measurement of temperature 11.4 Ideal-gas equation and absolute temperature 11.5 Thermal expansion 11.6 Specific heat capacity 11.7 Calorimetry 11.8 Change of state 11.9 Heat transfer 11.10 Newton’s law of cooling
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Class 11 Physics Chapter 14 Oscillations
Section Name Topic Name 14 Oscillations 14.1 Introduction 14.2 Periodic and oscilatory motions 14.3 Simple harmonic motion 14.4 Simple harmonic motion and uniform circular motion 14.5 Velocity and acceleration in simple harmonic motion 14.6 Force law for simple harmonic motion 14.7 Energy in simple harmonic motion 14.8 Some systems executing Simple Harmonic Motion 14.9 Damped simple harmonic motion 14.10 Forced oscillations and resonance
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Class 11th Physics Online Class For 100% Result
About Lesson

Translational degree of freedom:-

  • Translation means motion of the body as a whole from one point to another.
  • For example:
    • Consider the oxygen molecule;it has 2 oxygen atoms which are bonded together.
    • The 2 oxygen atoms along with the bond are considered as whole body.
    • When the body as a whole is moving from one point to another is known as translational.
    • Consider a molecule which is free to move in space and so it will need 3 coordinates(x, y, z) to specify its location.
    • Therefore it has 3 degrees of freedom.
    • Similarly a molecule which is free to move in a plane which is 2 dimensional and so it needs 2 coordinates to specify its location.
    • Therefore it has 2 degrees of freedom.
    • Similarly a molecule which is free to move in line it needs 1 coordinate to specify its location.
    • Therefore it has 1 degree of freedom.
  • Molecules of monoatomic gas have only translational degrees of freedom.This means gases which have only one atom.
  • For example:-Helium atom it consists of only one He atom.It will have translationaldegrees of freedom.
  • Each translational degree of freedom contributes a term that contains square of some variable of motion.
    • The variable of motion means the velocity (vx,vy,vz).
    • The term (1/2) mvx2 will contribute to energy.This is Kinetic energy which is involved with the motion of the molecule from one point to another.

In thermal equilibrium, the average of each such term is (1/2) kBT.

Kinetic Theory Notes

Rotational Degree of freedom

  • Independent rotations that specify the orientation of a body or system.
    • There is rotation of one part of the body with respect to the other part.
  • Rotational degree of freedom happens only in diatomic gas.
  • Diatomic molecules have rotational degrees of freedom in addition to translational degrees of freedom.
  • It is possible in diatomic molecules as 2 atoms are connected together by a bond.So the rotation of one atomw.r.t to other atom.
  • In diatomic there is translational in addition to that they have rotational degree of freedom also.
    • For example: – Two oxygen atoms joined together by a bond. There are two perpendicular axes.
    • There are 2 rotations possible along the two axes.
    • They have 3 translational degrees of freedom and also 2 rotational degree of rotation.
  • Therefore Rotational degree of freedom contributes a term to the energy that contains square of a rotational variable of motion.
  • Rotational variable of motion comes from angular momentum ω.
    • Linear velocity is vx,vy,vz. Whereas angular velocity is wx,wy,wz.
    • ER(rotational) = (1/2)(I1ω1)+(1/2)I2 ω2. These are 3 rotationaldegrees of freedom along the 2 perpendicular axes.
  • The total energy contribution due to the degrees of freedom for oxygen molecule.
    • There will be 3 translational degree of freedom (1/2)mxvx2,(1/2)myvy2,(1/2)mzvz2)
    • 2 rotational degree of freedom (1/2)I12ω12,(1/2)I22ω22
Class 11 Physics Chapter 13 Kinetic Theory Notes & NCERT Solution
Kinetic Theory Notes

Vibrational degree of freedom

  • Some molecules have a mode of vibration,i.e. its atoms oscillate along the inter-atomic axis like a one-dimensional oscillator.
  • This vibration is observed in some molecules.
    • For example:- CO atoms oscillate along the interatomic axis like a

one-dimensional oscillator.

  • Consider two 2 atoms they vibrate along the inter-atomic axis.
  • The vibrational energy terms contain square of vibrational variables of motion.
  • Total vibrational energy term Ev = (1/2) m (dy/dt)2+ (1/2) ky2 where

 (1/2) m(dy/dt)2=Kinetic energy and (1/2)ky2 =Potential energy and k=force constant one-dimensional oscillator.

  • The vibrational degree of freedom contributes 2 terms.
Class 11 Physics Chapter 13 Kinetic Theory Notes & NCERT Solution
Class 11 Physics Chapter 13 Kinetic Theory Notes & NCERT Solution
Kinetic Theory Notes
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