Mumphrey Science
← Force & Motion

Balanced or Unbalanced?

Pull on a rope from both sides and work out when the marker moves, when it stops, and why balanced does not mean nobody is pulling.

  1. 01Change the force on each side and observe the pattern of motion.
  2. 02Tell the difference between balanced and unbalanced forces.
  3. 03Stop the marker two different ways and compare them.
  4. 04Explain why an object only changes its motion when forces are unbalanced.

00 / 06 challenges solved

Predict first: on

Tug of war

Balanced

1 pull
1 pull

Balanced

The marker stays still

Both sides are pulling just as hard, so the forces are balanced and the marker stays still. Balanced does not mean there are no forces. There is a lot of force here, and it cancels out.

Challenges

0 of 6

  1. 01

    Make the marker move to the right.

    The side pulling harder wins. Put more pulls on the right than on the left.

  2. 02

    Make the marker move to the left.

    Now make the left side the stronger one.

  3. 03

    Make the marker move as fast as it can.

    The bigger the difference between the two sides, the faster it moves.

  4. 04

    Stop the marker moving, with people pulling on both sides.

    Make the two sides equal. They do not have to be zero.

  5. 05

    Hold it still with the strongest pull you can on both sides.

    Four pulls on the left and four on the right.

  6. 06

    Hold it still with nobody pulling at all.

    Take every pull off both sides.

Claim, Evidence, Reasoning

Before you writeLook back at the two ways you stopped the marker moving: four pulls on each side, and nobody pulling at all. What do you notice?