Projectile Motion as Two Independent Motions · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

A projectile is two motions in one

Science · Forces & Motion · ages 16-17
Name ______________________   Date ____________

  1. What is the only quantity the horizontal and vertical motions share?

    • Time
    • Mass
    • Sideways speed

  2. What is the horizontal acceleration of a projectile in flight?

    • 9.8 metres per second squared down
    • 0
    • 9.8 metres per second squared up

  3. Why does the horizontal velocity of a projectile stay constant?

    • Because gravity pushes sideways too
    • Because nothing pushes sideways
    • Because the mass holds it steady

  4. That ball leaves the bench at 2 metres per second sideways. About how far in metres from the bench does it land?

    Answer: ______________

  5. A ball rolls off a 1.25 m bench. Take g as 9.8. About how long in seconds is it in the air?

    Answer: ______________

  6. A heavy ball and a light ball roll off a bench together at the same speed. Hal says the heavy one lands first. Is Hal right?

    Circle one:   True   False

  7. Kaz puts the bench height in the horizontal list to find the flight time. Is Kaz right?

    • Yes, height belongs anywhere convenient
    • No, mass must be found before any time
    • No, height belongs in the vertical list and time comes from the fall

  8. A ball rolls off a 4.9 m ledge at 3 metres per second sideways. Take g as 9.8. Where does it land?

    • About 3 m out
    • About 4.9 m out
    • About 14.7 m out
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Answer key

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

A projectile is two motions in one W1-mt_OBgL97RFbb-s1

  1. Time · Solve one direction for t, then carry it across to the other.
  2. 0 · Nothing pushes sideways, so sideways velocity never changes.
  3. Because nothing pushes sideways · Sideways speed never changes when no sideways force acts.
  4. 1 · Sideways distance is speed times time: 2 times 0.5 is 1.
  5. 0.5 · 1.25 is 4.9 t squared, so t squared is about 0.25 and t is about 0.5.
  6. False · Mass never appears: gravity accelerates all masses equally.
  7. No, height belongs in the vertical list and time comes from the fall · Height is vertical travel, so only the vertical list with g can give t.
  8. About 3 m out · 4.9 is 4.9 t squared, so t is 1, and 3 times 1 is 3.
Worksheet · LightMySky