Students now embark on a second investigation by creating two pulley systems. On this page they are asked to consider how much force they must apply to lift the load off the table or floor.
Materials required include 2 pulleys, string, and a load to lift.
The two images show possible materials and how to attach the pulleys on a stiff piece of cardboard or wood. The load in the image is a binder clip with papers attached. The load can be anything that you can clip on or tie a string around. A coffee mug weighs enough and has a handle to tie. If you don’t have stiff cardboard or wood to hang the pulleys, you can use lab stands. Equally effective is to put a chair on top of a table and hang the pulley from a bar or slat. For the second system, the two pulleys should be at least 30 centimeters apart.
Read the instructions together and then be sure that students understand that the first task is to feel how much force they need to apply in order to lift the load in each of the 2 systems. You may ask them to predict before they construct the systems which will require the greater force.