Hobbies And Interests
Background
A simple pulley uses a wheel on an axle. Rope is threaded through a channel on the wheel, and an object is lifted as it is attached to the arrangement. Two or more pulleys can be used together in a compound pulley system. The rope starts from the upper pulley that is fixed and then it passes around the lower pulley and back up to the upper pulley. This system increases the lift capability of the pulley to more easily lift heavy objects. The block and tackle pulley arrangement is where multiple pulleys are mounted to different axles.
Materials
Gather a few materials to construct a pulley experiment. You will need three pulleys; two blocks, the kind for a pulley system; a tape measure; a spring scale; rope for the pulleys; and a 5-gallon bucket. Fill the bucket with sand or water. Measure the weight of the filled bucket on the spring scale. This will be your control weight. Find a safe location to build your pulley experiment, such as a garage beam or strong tree branch. The attachment point must be able to hold the weight of the filled bucket. Young children will need adult supervision.
Experiment
Arrange one of the pulleys into a simple pulley system with your rope. Tie the rope to the bucket and attach the other end to the spring scale. Record the weight. Also measure the amount of rope pulled to lift the bucket 6 feet with a simple pulley system and record the length. Create a compound pulley arrangement and perform the same experiment. Record your findings. Then create a block and tackle pulley system and record your new findings with the experiment.
Conclusions
After your experiment, chart your results. The results should have concluded that the simple pulley required the greatest human force, since you only used one pulley. The block and tackle pulley, however, gave the greatest advantage in lifting the heavy bucket. Create a graph showing what each weight measured on the scale and the length of rope needed to pull the bucket up 6 feet.