Modelling Motion in a Straight Line · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Setting up motion before calculating

Mathematics · Mechanics · ages 16-17
Name ______________________   Date ____________

  1. A model calls a sliding block a particle. What does that assume?

    • Its size and rotation do not matter
    • It has no mass
    • It moves at constant speed
    • It feels no gravity

  2. A runner goes 60 m east and then 60 m back west. How far did they travel in metres?

    Answer: ______________

  3. East is chosen as positive. A car has velocity negative 12 m/s. What does that mean?

    • It is moving west at 12 m/s
    • It is slowing down
    • It is stopped
    • It is accelerating east

  4. A runner goes 5 m out and 5 m back. What is the displacement in m?

    Answer: ______________

  5. Negative acceleration always means slowing down.

    Circle one:   True   False

  6. You move forwards while acceleration is negative. What happens?

    • You speed up at once
    • You stop immediately
    • You slow down, since the signs oppose

  7. A car moves east with velocity 20 m/s and acceleration negative 3 m/s squared. What is happening to its speed?

    • It is slowing down
    • It is speeding up
    • It stays exactly constant
    • It has stopped

  8. For the out-and-back runner, what are displacement and distance?

    • 0 m and 10 m
    • 10 m and 0 m
    • 5 m and 5 m

  9. A model calls a block smooth and light. What is it ignoring?

    • Speed and direction
    • Friction and mass
    • Time and distance

  10. Average velocity divides displacement by time for the out-and-back trip. What is it?

    • Large, since the path was long
    • Negative, since back was last
    • Zero, since finish minus start is zero
LightMySky · lightmysky.comW1-mt_no78_6w1rS-s1

Answer key

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

Setting up motion before calculating W1-mt_no78_6w1rS-s1

  1. Its size and rotation do not matter · Particle means all the mass sits at one point, so size, shape, and spin are ignored.
  2. 120 · Distance adds every leg: 60 plus 60 = 120 m, even though the displacement is zero.
  3. It is moving west at 12 m/s · The negative sign only records direction against the chosen positive: the car moves west at 12 m/s.
  4. 0 · Finish minus start is zero, whatever the path covered.
  5. False · It slows a forward motion but speeds up a backward one.
  6. You slow down, since the signs oppose · Opposite signs mean the velocity is shrinking.
  7. It is slowing down · Velocity points east while acceleration points west, so they oppose each other and the speed drops.
  8. 0 m and 10 m · Zero gap between start and finish, but 10 m of path.
  9. Friction and mass · Smooth denies friction and light denies worth-counting mass.
  10. Zero, since finish minus start is zero · A zero numerator gives zero, however long the run felt.
Worksheet · LightMySky