Force & Motion Vocabulary · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Force & Motion Vocabulary

Science · Forces & Motion · ages 9-11
Name ______________________   Date ____________

  1. What is a resultant force?

    • The single force with the same effect as all forces combined
    • The largest force acting on an object
    • The sum of all forces ignoring direction
    • The force of gravity only

  2. Which words describe forces that are equal in size and opposite in direction, so an object's motion does not change?

    • Balanced forces
    • Unbalanced forces
    • Resultant force

  3. A lever pivots around a fixed point called the fulcrum.

    Circle one:   True   False

  4. What is the single combined force left over when two or more forces act on an object called?

    • Moment
    • Resultant force
    • Fulcrum

  5. A 5 kg object has a net force of 50 N acting on it. What is its acceleration in m/s^2?

    Answer: ______________

  6. How do you calculate the moment (torque) of a force?

    • Force times perpendicular distance from pivot
    • Force times mass
    • Force divided by distance
    • Mass times acceleration

  7. A force pushes right with strength 7. Another force pushes left with strength 4. What is the size of the resultant force?

    Right push7Left push4

    Answer: ______________

  8. One person pushes a box harder than another person pushing from the other side. Are these forces balanced or unbalanced?

    >
    • Balanced forces
    • Resultant force is zero
    • Unbalanced forces

  9. A heavier friend sits close to the fulcrum, and a lighter friend sits far from the fulcrum. The seesaw balances. What best explains why?

    Heavy,close6Light, far6
    • The heavier friend's push is always bigger, so it never truly balances
    • Only the distance from the fulcrum matters, not the weight
    • The moment on each side is equal

  10. Mia says, "Since both people are pushing the box, the forces must be balanced." What is wrong with her statement?

    • Balanced forces always make objects speed up
    • Forces also have to be equal in size and opposite in direction to be balanced, not just present
    • Only one force can act on an object at a time
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Answer key

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

Force & Motion Vocabulary W1-mt_F3ATPTCYm6-s1

  1. The single force with the same effect as all forces combined · The resultant force is the vector sum of all forces. It represents the combined effect of all forces acting on an object.
  2. Balanced forces · Balanced forces are equal but opposite, so they cancel out and nothing about the motion changes.
  3. True · The fulcrum is the fixed point a lever turns around.
  4. Resultant force · Add up every force acting on the object, and what's left over is the resultant force.
  5. 10 · Newton's second law: acceleration = force / mass. 50 N / 5 kg = 10 m/s^2.
  6. Force times perpendicular distance from pivot · Torque (moment) equals force multiplied by the perpendicular distance from the pivot to the line of action of the force.
  7. 3 · The forces pull in opposite directions, so subtract the smaller one from the bigger one: 7 minus 4 is 3.
  8. Unbalanced forces · The two pushes are different sizes, so they do not cancel out. That makes them unbalanced forces.
  9. The moment on each side is equal · Even though the weights are different, the heavier friend sits closer to the fulcrum, so both sides create the same moment and the seesaw balances.
  10. Forces also have to be equal in size and opposite in direction to be balanced, not just present · Two forces being present isn't enough. They also have to be equal in size and pushing in opposite directions to be balanced.
Worksheet · LightMySky