8th grade · Science · Unit 9 of 16
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.
Alabama Course of Study content standard: 8.9; 8.10; 8.11 · how forces and mass affect acceleration, and Newton's laws
How we explain it
Children can open this short lesson before they practice.
- Speed = distance ÷ time. Velocity is speed with a direction.
- Force is measured in newtons. Friction and gravity are forces.
- 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 Alabama
In the Alabama Course of Study, this is unit 9 of 16 in 8th grade Science, after Speed, Velocity & Motion Graphs and before Newton's Laws.
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.
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What is acceleration?
- being at rest
- a change in speed or direction over time
- steady speed
- gravity only
a change in speed or direction over time
Hint: Speeding up, slowing down and turning are all acceleration.
Question 2
Newton’s third law says that for every action there is…
- no reaction
- a smaller reaction
- an equal and opposite reaction
- a bigger reaction
an equal and opposite reaction
Hint: A rocket pushes gas down and the gas pushes the rocket up.
Question 3
What is a force?
- a speed
- a mass
- a kind of energy
- a push or a pull
a push or a pull
Hint: Forces are measured in newtons (N).
Question 4
Balanced forces on an object cause…
- acceleration
- a faster speed
- no change in its motion
- a turn
no change in its motion
Hint: A book on a table has balanced forces.
Question 5
What is the difference between mass and weight?
- mass is the amount of matter, and weight is the force of gravity on it
- mass is a force
- they are the same
- weight is the amount of matter
mass is the amount of matter, and weight is the force of gravity on it
Hint: Your mass is the same on the Moon, but your weight is less.
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 moving fast
- the object is not moving
the object is not moving
Hint: Distance does not change.