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8th grade · Science · Unit 7 of 10

Motion, Forces & Newton’s Laws

Speed, velocity, acceleration, friction and the Laws of Motion.

What your child practices

Practices speed, velocity, acceleration, forces, friction, gravity and Newton's three Laws of Motion, with stability. It follows the Grade 8 science skill descriptors on motion and stability and the Laws of Motion in the New Brunswick curriculum.

Minnesota K-12 Academic Standards benchmark: 8P.1.2.1.2 · how an object's motion depends on the forces on it and its mass

How we explain it

Children can open this short lesson before they practice.

  1. Speed = distance ÷ time. Velocity is speed with a direction.
  2. Force is measured in newtons. Friction and gravity are forces.
  3. Newton’s laws: objects keep doing what they’re doing unless a force acts; more force means more acceleration; every push has an equal push back.

Example: A cyclist rides 30 m in 6 s. What is her speed? Speed = distance ÷ time. 30 ÷ 6 = 5. Answer: 5 m/s

Motion, Forces & Newton’s Laws in Minnesota

In the Minnesota K-12 Academic Standards, this is unit 7 of 10 in 8th grade Science, after Newton's Laws and before Kinetic & Potential Energy.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Minnesota Department of Education (MDE)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    What is gravity?

    • a type of speed
    • a light
    • a force that pulls objects toward each other
    • a force that pushes objects apart

  2. Question 2

    What is inertia?

    • a speed
    • a kind of friction
    • a force
    • an object’s tendency to keep doing what it is doing

  3. Question 3

    A 2 kg object accelerates at 3 m/s². What force acts on it?

    • 5 N
    • 1.5 N
    • 6 N
    • 9 N

  4. Question 4

    If the same force pushes a light cart and a heavy cart, which accelerates more?

    • both the same
    • neither
    • the light cart
    • the heavy cart

  5. Question 5

    Balanced forces on an object cause…

    • a turn
    • a faster speed
    • acceleration
    • no change in its motion

  6. Question 6

    On a distance-time graph, what does a flat horizontal line mean?

    • the object is slowing
    • the object is speeding up
    • the object is not moving
    • the object is moving fast

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