Torque & Angular Momentum
- The rotational analogue of force is moment of force (Torque).
- If a force acts on a single particle at a point P whose position with respect to the origin O is given by the position vector r the moment of the force acting on the particle with respect to the origin O is defined as the vector product t = r × F = rF sinΘ
- The quantity angular momentum is the rotational analogue of linear momentum.
- It could also be referred to as moment of (linear) momentum.
- l = r × p
- Rotational analogue of Newton’s second law for the translational motion of a single particle: dl/st = τ
Torque and angular momentum of system of particles:
Equilibrium of Rigid Body
- A force changes the translational state of the motion of the rigid body, i.e. it changes its total linear momentum.
- A torque changes the rotational state of motion of the rigid body, i.e. it changes the total angular momentum of the body
Note: Unless stated otherwise, we shall deal with only external forces and torques.
- A rigid body is said to be in mechanical equilibrium, if both its linear momentum and angular momentum are not changing with time. This means
- Total force should be zero => Translational Equilibrium
- Total torque should be zero => Rotational Equilibrium
- When you open the lid of a jar , you apply couple on it
- An ideal lever is essentially a light rod pivoted at a point along its length. This point is called the fulcrum
- The lever is a system in mechanical equilibrium.
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Class 11 Physics Chapter 1 Physical World
Class 11 Physics Chapter 2 Unit and Measurements
Class 11 Physics Chapter 3 Motion In A Straight Line
Class 11 Physics Chapter 4 Motion In A Plane
Class 11 Physics Chapter 5 Laws of motion
Class 11 Physics Chapter 6 Work Energy and Power
Class 11 Physics Chapter 7 Rotation motion
Class 11 Physics Chapter 8 Gravitation
Class 11 Physics Chapter 9 mechanics properties of solid
Class 11 Physics Chapter 10 Mechanical Properties of Fluids
Class 11 Physics Chapter 11 Thermal Properties of matter
Class 11 Physics Chapter 12 Thermodynamics
Class 11 Physics Chapter 13 Kinetic Theory
Class 11 Physics Chapter 14 Oscillations
Class 11 Physics Chapter 15 Waves
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