Torque

• Torque of a force about any point is equal to the product of the force and perpandicular distance of the line of action of force from the point.
  τ= Force x perpandicular distance from line of action from point = Frsinθ =(Fsinθ)r
  or,
  τ= (component of force perpandicular to position vector) x (position vector)
  
• Unite of torque (a) MKS system --- N-m (b) CGS system --- dyne-cm.
  
• Dimension of torque is ML²T^-2
  
• In vector form τ=F x r
  
• Torque is a vector quantity having direction perpandicular to the plane of force and position vector and its direction is given by right hand rule.
  
• If the torque acting on a body tends to rotate in anticlockwise direction then torque is positive and if it tends to rotate the body in clockwise direction then the is negative.
  
• If the body s acted upon by more then one forces then total torque on the body is the vector sum of each torque.
  
• τ= dJ/dt , where J is the angular momentum of the body.
  
• The more is the value of r , more will be the torque and it would be easier to rotate the object.
  
• Work done by the torque is ∫>τdθ = Torque x angular displacement. here limits of integration goes from θ₁ to θ₂