Momentum Calculation and Conservation

Key Concepts

• Momentum is a property of moving objects.
  • If an object is not moving, its momentum is zero.
  • This is an important exam fact.

Momentum Formula

• Formula: ( \text{Momentum} = \text{Mass} \times \text{Velocity} )
  • Unit: kilogram meters per second (kg m/s)
  • Note: This formula is not provided in exams; memorization is required.

Examples

1. Non-moving Object:
   • Car with Mass: 1000 kg
   • Velocity: 0 m/s
   • Momentum: 0 (since object is not moving)
2. Moving Object:
   • Car with Mass: 1000 kg
   • Velocity: 20 m/s
   • Momentum: ( 1000 \times 20 = 20,000 ) kg m/s

Conservation of Momentum

• In a closed system, the total momentum before an event equals the total momentum after the event.
  • Known as the Conservation of Momentum.

Example Scenarios

1. Van and Stationary Car:

   • Before collision: Van has momentum (mass x velocity); car has no momentum.
   • After collision: Both move together with momentum equal to the van's initial momentum.
   • Total momentum conserved in collision.

2. Cannon and Cannonball:

   • Before firing: Both cannon and cannonball are stationary, total momentum = 0.
   • After firing: Cannonball moves forward, cannon recoils backward.
   • Forward momentum of the cannonball equals backward momentum of the cannon.
   • Total momentum after firing remains 0, showing momentum is conserved.

Additional Resources

• Practice questions available in the revision workbook linked in the video.