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Lesson · Grade 6 · Science

Balanced and Unbalanced Forces in Sport and Play

  • Grade 6
  • Science
  • 1 min 6 s
  • British Columbia
  • BC6-SC-13

One labelled diagram on a strip of grass builds up three everyday examples, with each force drawn as an arrow whose length shows its strength: sitting on a chair (gravity and the chair's push are equal, so the forces are balanced and you stay still), tug of war (equal pulls keep the rope still, but a harder pull makes the forces unbalanced and the rope starts to move), and kicking a ball (the kick makes the ball speed up, then friction slows it to a stop). It ends on the recap that balanced forces do not change motion but unbalanced forces do.

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In one sentence

The question this lesson answers

Do forces always make things move?

When you sit on a chair, gravity pulls you down.

Transcript

What the lesson says

Do forces always make things move?

When you sit on a chair, gravity pulls you down.

The chair pushes up on you just as hard, so its arrow is just as long.

Equal forces in opposite directions are balanced, so you stay still.

In tug of war, two players pull the rope in opposite directions.

When both pulls are equal, the forces are balanced and the rope stays still.

Now the player on the right pulls harder.

The forces are now unbalanced, so the rope starts to move toward the stronger pull.

When you kick a ball, your foot gives it a big push.

Nothing pushes back as hard, so the forces are unbalanced and the ball speeds up.

As the ball rolls, friction from the grass pushes back on it.

This unbalanced force slows the ball down until it stops.

Balanced forces do not change motion, but unbalanced forces do.

Curriculum

Where this fits

British Columbia, Grade 6

Science, Physics: effects of balanced and unbalanced forces in daily physical activitiesBC6-SC-13

Previous: Newton's Third Law: Equal and Opposite ForcesNext: Gravity: Every Object Pulls on Every Other Object

The outcomes and strands follow the British Columbia curriculum.

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