Momentum and Collisions - Mission MC7 Detailed Help

A 120-kg red bumper car moving east at 2.00 m/s collides with a 150-kg blue car moving east at 1.20 m/s. After the collision, the red car is moving east at 1.20 m/s and the blue car is moving east at 1.84 m/s. Fill in the momentum table and determine if momentum is conserved (within 1 percent). Use the notation that east is the positive direction and west is the negative direction.

(Note: Your numerical values are selected at random and likely different from the numbers listed here.)

The momentum (p) of an object can be calculated from knowledge of its mass (m) and velocity (v) using the formula:

p = m • v

The ultimate goal of this analysis is to determine if momentum is conserved by the collision. The following strategy will prove effective.
  • Since the mass and the velocity of each car is given for before and after the collision, the momentum values can be calculated (see Formula Frenzy section).
  • The total momentum of the system is simply the sum of the individual momentum values of the two cars. Once individual values have been calculated, the total momentum of the system can be calculated.
  • Finally, a comparison of the pre-collision system momentum and post-collision system momentum reveals whether or not momentum is conserved. Momentum is said to be conserved if the system possesses the same amount of total momentum before the collision as after the collision (or at least within 1%).


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