I pull the trigger of the toy gun which releases elastic energy in a spring in the gun. That energy is transferred to kinetic energy in the dart which hit the poker decks. Gravitational energy causes the poker decks to fall, changing to kinetic energy in the tennis ball. The tennis ball gains more speed form the gravitational energy of the slope, and then collides with the toy car giving it kinetic energy. As the car moves, it transfers it kinetic energy into the string which raises the shelf below. Gravitational energy causes the second ball to roll until it hits the juice box. After the juice box falls over, gravity pulls the coconut water in to the paper cup.

Link  :  https://www.youtube.com/watch?v=ZcX1b22vPqw&feature=youtu.be

Step A: The toy gun fires a dart that pushes over the decks of poker cards.
Step B: The poker decks fall down in order like dominos, which pushes the first tennis ball rolls over the edge.
Step C: The tennis ball rolls down the first slope and onto the next track, knocking the toy car forward and falls down.
Step D: The car pulls a string that raises the track below.
Step E: The third track raises and makes the second ball rolls over the edge and falls down along the second slope.
Step F: The second ball knocks down the juice box, which falls on its side.
Step G: The orange juice runs into the paper cup.