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Adding Mass to a Moving System quiz

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  • What type of collision occurs when a box is dropped onto a moving sled and they move together afterward?
    This is a completely inelastic collision, where the two objects stick together and move with the same final velocity.
  • What is the initial horizontal velocity of the box before it lands on the sled?
    The initial horizontal velocity of the box is 0 m/s because it is dropped vertically.
  • How do you calculate the final velocity of the combined sled and box system after the collision?
    Use conservation of momentum: (m1*v1_initial + m2*v2_initial) = (m1 + m2)*v_final.
  • What is the final velocity of the sled and box after the box is dropped onto the sled?
    The final velocity is 7 m/s.
  • Why does the velocity of the sled decrease after the box is added?
    The velocity decreases because the total mass increases, and to conserve momentum, the velocity must decrease proportionally.
  • What is the initial momentum of the sled before the box is dropped?
    The initial momentum is 70 kg * 10 m/s = 700 kg·m/s.
  • What is the change in momentum (Δp) of the box after it lands on the sled?
    The change in momentum for the box is 210 kg·m/s.
  • How do you calculate the change in momentum for the box?
    Δp = m2 * (v_final - v_initial) = 30 kg * (7 m/s - 0 m/s) = 210 kg·m/s.
  • What is the change in momentum for the sled after the collision?
    The change in momentum for the sled is -210 kg·m/s.
  • How do you calculate the change in momentum for the sled?
    Δp = m1 * (v_final - v_initial) = 70 kg * (7 m/s - 10 m/s) = -210 kg·m/s.
  • Why are the changes in momentum for the sled and box equal in magnitude but opposite in sign?
    Because momentum is conserved, the gain in momentum by the box is exactly balanced by the loss from the sled.
  • What principle explains the exchange of momentum between the sled and the box?
    The conservation of momentum explains the exchange, ensuring the total system momentum remains constant.
  • If the box had an initial horizontal velocity, how would the calculation change?
    You would include the box's initial horizontal momentum in the conservation of momentum equation.
  • What must be true about the final velocities of the sled and box after the collision?
    They must have the same final velocity since they move together as one object.
  • What does the sled do to the box when the box lands on it?
    The sled accelerates the box to its own velocity, transferring some of its momentum to the box.