Momentum

 

 
2.5

 Momentum

 
  Momentum : product of mass and velocity  
  \(p=m\times v\)  
     
 
  The principle of conservation of momentum  
  The total momentum of a system is constant if there are no external forces acting on the system  
     
 

Types of situations involving principle of conservation of momentum

  • Collision: Total momentum before collision is equal to the total momentum after the collision
  • Explosion: The total momentum before and after the explosion is zero
 
Elastic collision Inelastic collision
Momentum, total energy and kinetic energy are all conserved. Momentum and total energy conserved, but kinetic energy is not conserved.
\(m_1u_1+m_2u_2=m_1v_1+m_2v_2\) \(m_1u_1+m_2u_2=(m_1+m_2)v\)
 
  Explosion  
 

Total momentum before and after explosion is zero.

\(m_1v_1=-m_2v_2\)

 
     
   
     
 

Example:

  • rifle firing a bullet
  • rocket launching
 
     
 
 

 

Momentum

 

 
2.5

 Momentum

 
  Momentum : product of mass and velocity  
  \(p=m\times v\)  
     
 
  The principle of conservation of momentum  
  The total momentum of a system is constant if there are no external forces acting on the system  
     
 

Types of situations involving principle of conservation of momentum

  • Collision: Total momentum before collision is equal to the total momentum after the collision
  • Explosion: The total momentum before and after the explosion is zero
 
Elastic collision Inelastic collision
Momentum, total energy and kinetic energy are all conserved. Momentum and total energy conserved, but kinetic energy is not conserved.
\(m_1u_1+m_2u_2=m_1v_1+m_2v_2\) \(m_1u_1+m_2u_2=(m_1+m_2)v\)
 
  Explosion  
 

Total momentum before and after explosion is zero.

\(m_1v_1=-m_2v_2\)

 
     
   
     
 

Example:

  • rifle firing a bullet
  • rocket launching