Momentum and Collisions Quiz

Grade 11 · Science · Quiz

Test your ability to apply conservation of momentum and analyze elastic and inelastic collision problems.

Questions

  1. A 1500 kg car moving at 20 m/s has what momentum?

    1. 75 kg·m/s
    2. 750 kg·m/s
    3. 30000 kg·m/s
    4. 300 kg·m/s
    Show answer

    Answer: 30000 kg·m/s

    p = mv = 1500 × 20 = 30,000 kg·m/s.

  2. A 0.5 kg ball is hit by a bat, changing its velocity from -15 m/s to +25 m/s. What impulse did the bat deliver?

    1. 5 N·s
    2. 20 N·s
    3. 12.5 N·s
    4. 7.5 N·s
    Show answer

    Answer: 20 N·s

    Impulse = Δp = m(v_f - v_i) = 0.5 × (25 - (-15)) = 0.5 × 40 = 20 N·s.

  3. In which scenario is kinetic energy conserved during a collision?

    1. A car crash where both cars crumple
    2. Two billiard balls colliding and bouncing off each other perfectly
    3. A ball of clay sticking to a wall
    4. A bullet embedding itself in a block of wood
    Show answer

    Answer: Two billiard balls colliding and bouncing off each other perfectly

    An elastic collision conserves kinetic energy. Ideal billiard ball collisions closely approximate elastic; the other options involve deformation and energy loss.

  4. A 3 kg object moving at 4 m/s east and a 2 kg object moving at 6 m/s west collide and stick together. What is the final velocity?

    1. 0 m/s
    2. 0.5 m/s east
    3. 0.5 m/s west
    4. 0 m/s west
    Show answer

    Answer: 0 m/s

    Taking east as positive: p_net = (3)(4) + (2)(-6) = 12 - 12 = 0 kg·m/s. Final velocity = 0/(3+2) = 0 m/s.

  5. A rocket in space expels gas to accelerate. This demonstrates which principle?

    1. Conservation of Energy
    2. Conservation of Momentum
    3. Newton's First Law only
    4. Conservation of Charge
    Show answer

    Answer: Conservation of Momentum

    Rockets work by conservation of momentum. Gas is expelled backward; the rocket gains equal and opposite momentum forward (Newton's 3rd Law is the mechanism, but momentum conservation is the principle).

  6. A 4 kg object at rest explodes into two pieces. Piece A (1 kg) moves at 12 m/s north. What is the velocity of Piece B (3 kg)?

    1. 4 m/s south
    2. 36 m/s north
    3. 12 m/s south
    4. 4 m/s north
    Show answer

    Answer: 4 m/s south

    Total initial momentum = 0. After explosion: p_A + p_B = 0. p_A = 1×12 = 12 kg·m/s north. p_B = -12 kg·m/s = 12 kg·m/s south. v_B = -12/3 = 4 m/s south.

  7. The total momentum of an isolated system is conserved even when internal forces act between objects within the system.

    Show answer

    Answer: True

    Internal forces between objects within a system are Newton's third law pairs — they cancel in pairs. Only external forces change the system's total momentum.

  8. The area under a force-time graph represents the _____ delivered to an object.

    Show answer

    Answer: impulse

    Impulse J = FΔt for constant force, or the integral of F dt for varying force. The area under a force-time graph gives total impulse, which equals the change in momentum.

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