Conservation of Momentum

• • Objects moving at the SAME VELOCITY, a MORE MASSIVE object has GREATER INERTIA in motion therefore that is the one which is more difficult to stop.
  • When two objects of the SAME MASS has DIFFERENT velocities; the one with HIGHER VELOCITY is the one which is more difficult to stop.
• Momentum:

  • The difficulty encountered in bringing the moving objects to stop.
  • Also called the "mass in motion or inertia in motion."
  • The amount of an object’s momentum is dependent on two variables: the amount in the mass of the object that is moving and velocity of the moving object. Therefore, the momentum of an object is equal to the mass of the object times its velocity.

  Mathematically, it can be expressed as

  Momentum = mass • velocity
• Force multiplied to time is equal to the mass multiplied to the change in velocity; where Force multiplied to time refers to impulse and the mass multiplied to the velocity is called momentum.

  • Impulse = Change in momentum
  • I = F • t
• Sample Problem:

  • Momentum

  1. A bowling ball whose mass is 4.0 kg is rolling at a rate of 2.5 m/s. What is its momentum?

  GIVEN:

  • m = 4.0 kg
  • v = 2.5 m/s

  REQUIRED:

  • Momentum

  EQUATION:

  • p = mv

  SOLUTION:

  • p = (4.0kg)(2.5m/s)

  ANSWER:

  • 10 Kg-m/s
• Guide:

  A) Kg-m/s

  B) g-cm/s

  C) Kg

  D) m/s

  E) g

  F) cm/s

  
• Sample Problem:

  • Impulse

  1. A 17.05 Kg ball rolls at a velocity of 38.3 m/s bounced back after hitting the drum full of water with a force of 18 N at 15 seconds. What is its Impulse (I) or its change in momentum?

  GIVEN:

  • m = 17.05 Kg
  • v = 38.3 m/s
  • F = 18 N
  • t = 15 s

  REQUIRED:

  • Impulse

  EQUATION:

  • I = F . t

  SOLUTION:

  • I = (18 N) . (15 s)

  ANSWER:

  • I = 270 Ns