Momentum and Its Conservation · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

How motion is shared in crashes

Science · Forces & Motion · ages 14-16
Name ______________________   Date ____________

  1. Momentum has a direction, pointing the way the object moves.

    Circle one:   True   False

  2. What do you multiply to find momentum?

    • Mass and velocity
    • Mass and force
    • Velocity and time

  3. Which unit belongs to momentum?

    • kg
    • m/s
    • kg m/s

  4. A 1 kg trolley at 6 m/s hits a resting 2 kg trolley and sticks to it. The 3 kg lump keeps the 6 kg m/s. How fast does it move?

    • 2 m/s
    • 3 m/s
    • 6 m/s

  5. A 2 kg trolley rolls at 3 m/s. What is its momentum in kg m/s? Type the number.

    Answer: ______________

  6. Two trolleys start at rest and push apart in an explosion. What must be true after?

    • They both stay at rest
    • They move apart in opposite directions with momentums that cancel
    • They move the same way at the same speed

  7. Two matching trolleys collide and stick. One moved at 4 m/s and the other sat still. Why is the joined speed below 4 m/s?

    • Some momentum vanishes as heat and sound
    • The same momentum is shared by twice the mass
    • Friction with the track steals half the speed

  8. A learner totals a head-on crash as 5 plus 5 equals 10, but the trolleys moved toward each other. What is the mistake?

    • The masses were added to the velocities
    • The unit kg m/s was left out
    • The signs were ignored, so opposite momentums added instead of cancelling
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How motion is shared in crashes W1-mt_Nn5_DMbK1_-s1

  1. True · Momentum is a vector with the same direction as velocity.
  2. Mass and velocity · Momentum is mass times velocity.
  3. kg m/s · Mass in kg times velocity in m/s gives kg m/s.
  4. 2 m/s · Divide total momentum by joined mass: 6 divided by 3 is 2.
  5. 6 · Multiply mass by velocity: 2 times 3 is 6.
  6. They move apart in opposite directions with momentums that cancel · They fly apart in opposite directions, keeping the total at zero.
  7. The same momentum is shared by twice the mass · The momentum math stays exact, but twice the mass means half the speed.
  8. The signs were ignored, so opposite momentums added instead of cancelling · Toward each other means opposite signs, so 5 and minus 5 cancel.
Worksheet · LightMySky