Newton's First & Second Laws · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Newton's First and Second Laws

Science · Forces & Motion · ages 12-13
Name ______________________   Date ____________

  1. An air-hockey puck floats on a cushion of air. After a player hits it, the puck glides at almost the same speed until it reaches the wall.

    Circle one:   True   False

  2. What net force in newtons is needed to accelerate a 5 kg object at 3 m/s²?

    Answer: ______________

  3. Two objects are pushed with the same force. Object A has mass 2 kg, Object B has mass 10 kg. Which accelerates more?

    • Object A
    • Object B
    • Both accelerate the same
    • Neither accelerates

  4. A spacecraft in deep space fires its engines for 10 seconds, then shuts them off. What happens after the engines stop?

    • It immediately stops
    • It slows down gradually
    • It continues at constant velocity forever
    • It accelerates faster

  5. Why do you need a seatbelt if a car stops suddenly?

    • Your body keeps moving forward until a force stops it
    • The car pushes you backward
    • Your body speeds up by itself

  6. A 30 kg canoe and a 15 kg kayak both need to accelerate at 2 m/s². Which one needs more force?

    Canoe (30kg)60Kayak (15kg)30
    • The kayak needs more force
    • They need the same force
    • The canoe needs more force

  7. A cyclist goes from standing still to 12 m/s in 4 seconds. Her brother says her acceleration is 48 m/s². Is he right?

    Circle one:   True   False

  8. A 24 N force pushes a 6 kg trolley. What is the trolley's acceleration?

    • 144 m/s²
    • 4 m/s²
    • 18 m/s²

  9. A force of 60 N makes a cart accelerate at 4 m/s². What is the mass of the cart?

    • 240 kg
    • 64 kg
    • 15 kg

  10. A force of 54 N gives a sledge an acceleration of 6 m/s². What is the mass of the sledge, in kg?

    Answer: ______________

LightMySky · lightmysky.comW1-mt_tXxxCFl32J-s1

Answer key

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

Newton's First and Second Laws W1-mt_tXxxCFl32J-s1

  1. True · The cushion of air means almost no friction, so almost no resultant force acts on the puck. Newton's First Law says it keeps its speed until the wall stops it.
  2. 15 · Using F = ma: F = 5 kg x 3 m/s² = 15 N.
  3. Object A · Acceleration = force/mass. Same force on smaller mass gives larger acceleration. Object A (2 kg) accelerates 5x more than Object B (10 kg).
  4. It continues at constant velocity forever · With no friction or external forces in deep space, Newton's first law says the spacecraft continues at constant velocity indefinitely.
  5. Your body keeps moving forward until a force stops it · Your body was moving with the car. Newton's First Law says it keeps moving until a force, the seatbelt, acts on it.
  6. The canoe needs more force · F = m × a. With the same acceleration, more mass means more force: 60 N for the canoe versus 30 N for the kayak.
  7. False · She gains 12 m/s over 4 seconds, so her acceleration is 12 ÷ 4 = 3 m/s², not 48 m/s².
  8. 4 m/s² · Rearrange F = m × a to a = F ÷ m = 24 ÷ 6 = 4 m/s².
  9. 15 kg · Rearrange F = m × a to m = F ÷ a = 60 ÷ 4 = 15 kg.
  10. 9 · Rearrange F = m × a to m = F ÷ a = 54 ÷ 6 = 9 kg.
Worksheet · LightMySky