Impulse and Momentum

Impulse and Momentum

Defining Impulse and Momentum

  • Momentum is a vector quantity and is described as the mass of an object multiplied by its velocity.
  • Impulse is the product of the force applied to an object and the time during which it is applied.

Impulse-Momentum Theorem

  • The Impulse-Momentum Theorem states that the change in momentum of an object equals the impulse exerted on it.
  • In equation form, it is represented as: Ft = Δ(mv), where F is the force applied, t is the time, m is the mass of the object, and v is its velocity.
  • If a net force is applied to an object, it will experience a change in momentum.

Impulse and Real-World Situations

  • The concept of impulse can be applied in real-life situations. For example, when you catch a cricket ball, if you move your hand backwards on catching, you increase the time of contact which decreases the rate of change of momentum, leading to a smaller force on your hands.
  • This concept is also used in safety technologies such as airbags and helmets, where they increase the time of impact, reducing the force experienced.

Conservation of Momentum

  • The principle of conservation of momentum states that the total momentum of a closed system is constant if no external forces act upon it.
  • This principle is applicable for all types of collisions – elastic, inelastic and perfectly inelastic.

Momentum during Collisions

  • In elastic collisions, both momentum and kinetic energy are conserved, meaning the total momentum and kinetic energy before the impact is the same as after the impact.
  • In inelastic collisions, only momentum is conserved, and some of the kinetic energy is lost to other forms such as sound, heat or deformation of the objects.
  • In perfectly inelastic collisions, the two objects stick together and move as one after the impact, but the momentum remains conserved.

Momentum, Impulse and Forces

  • The concepts of impulse and momentum are crucial in understanding how forces can affect the motion of an object.
  • They allow us to calculate the forces involved in a collision or explosion and predict an object’s motion post an impact or force application.