Trolley forces
Classroom Activity
for 11-14
What the Activity is for
Motion of a trolley.
The purpose of this activity is to involve pupils in discussion about resultant forces. How will various forces affect the motion of the trolley?
What to Prepare
- dynamics trolley
- two pulleys
- two sets of 100 gram masses and hangers
What Happens During this Activity
With the trolley set up as in the diagram, pupils can predict and observe the effect of different combinations of forces acting on the trolley. There are two important strands to the discussion. In which direction will the trolley move? What type of motion (speeding up? slowing down? constant speed?) will result from forces which do not add to zero?
Whilst you have a situation where all forces add to zero, it is a good idea to invite someone to cut the string on one side of the trolley. The resulting discussion will allow you to assess how far the learners have appreciated the ideas (the trolley gets going in one direction due to the action of the resultant force).
You might like to use this model to support the discussion about their predictions:
