Problem 7.9: An explosive collision


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Two carts are in close proximity. A massless spring is attached to the end of the red cart and is compressed. The massless spring is released such that the two carts are "pushed" apart as shown in the animation (position is given in meters and time is given in seconds). The mass of the green cart is 1.5 kg. Consider a system made up of the two carts and the massless spring. Restart.

  1. What is the velocity of the center of mass of the carts after the massless spring is released (assume that since the spring is massless it cannot have a kinetic energy)?
  2. What is the mass of the red cart?
  3. What is the change in kinetic energy of the system due to the release of the spring?
  4. What was the change in potential energy of the spring?