Task 4

Materials and tools for a working group:

2 pendulums with differently heavy bobs (eg plasticine)

The goal of the task is to find out whether the pendulum oscillation rate depends on how heavy pendulum bobis. Pupils consider the following predictions:

• I think both of pendulums will swing the same rate.
• I think, the swing of pendulum will be faster if the pendulum bob is heavier.
• I think, the swing of pendulum will be faster if the pendulum bob is lighter

After making prediction, it is important to be aimed at procedure suitable for its verification. In addition, it is necessary to ensure that the weight of the pendulum bob is the only variable that will be changed for two measurements (control and experimental). This means that you need to use the same stand, the same length of string and the same sized (volume) pendulum bobof the same shape, preferably the ball. The teacher warns and calls on the pupils to try to figure out how to create two pendulum bobs that are of same size (volume), the same shape, but varyin weight.

If the teacher does not have enough time to discuss with pupils appropriate research procedures, he/she can propose the procedure himself. The easiest way is to use plasticine. For example, a heavier ball of plasticine can be obtained by replacing a piece of plasticine with a metal ball, which is pressed into a small amount of plasticine. In the same way, a lighter ball can also be created if we replace the plasticine with, for example, polystyrene. Alternatively, it is possible to use a polystyrene bead and the second, equally large, of plasticine. In the event that pupils do not propose a procedure, the procedure proposed by the teacher is recorded by the pupils in the section specified in the worksheet. Then pupils measure the number of swings for a lighter and heavier pendulum bobs, and write the results in numerical form and then create a diagram from the numerical values. On the basis of the diagram they conclude and answer the research question. In this case, the weight of the pendulum does not depend on the weight of the weight.