Forces and Motion


Classroom Activity for 5-11 Supporting Physics Teaching

What the Activity is for

Here we start to look at forces that can oppose the gravity force and so prevent falling. This is a very simple quick introduction, and could be optional, but does open up the possibility of discussing some of the variation in speed over a fall.

What to Prepare

  • A soft toy, or other object to focus on
  • Some string
  • Some weak elastic
  • Some soft foam
  • Some cardboard gravity arrows
  • Some cardboard support arrows

What Happens During this Activity

Start by dropping the soft toy, this time focusing on the force of gravity that causes the falling. Building on this start, now open up a new question:

Teacher: How can we stop the soft toy falling?

Move the discussion towards providing some support for the soft toy: later these will be formalised as support forces, but that is a step beyond what you should aim to achieve here.

The endpoint of this discussion is simply to suggest that there could be forces which oppose the gravity force. These forces arise from the physical environment. It is useful to have a physical environment which distorts in order to provide the force, so we'd suggest starting with supporting this toy by using soft foam or by using weak elastic.

It is a further leap of the imagination to see the string as distorting to exert a force (a tension force), or to see the tabletop or floor as distorting to exert a force(a compression force). That is a step which may or may not prove useful for you to take.

The situation where there is no change in speed, because there is no speed at any time, is a special case of equilibrium: the forces acting on soft toy add up to zero.

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