3 CHANGING THE MOVEMENT OF AN OBJECT REQUIRES A NET FORCE TO BE ACTING ON IT

Task 6

WORKSHEET

Materials and tools for a working group:

isosceles lever from previous task, 2 lumps of plasticine of similar size

Task 6 is a direct application of research findings from Task 5, so it is advisable if they are implemented in this sequence. The aim of the task is to make pupils aware of the use of an isosceles lever when comparing the weights of objects (the principle of isosceles balance). Pupils have two lumps of plasticine of similar size, the aim of which is to determine which one is larger (thinks heavier as both articles are of the same substance), have an isosceles (swing) to determine. It is advisable for the teacher to lead the pupils first to compare two plasticine chests, for example, by hand gripping, so that the pupils find that the minor differences are rather difficult to detect. We do the research to make sure we compare.

An interesting task is to encourage pupils to try to propose their own way of finding out which of the two plasticine lumps is larger. If the teacher entrusts such a task, he or she should give enough time to the pupils to prepare the answer, and should also be given adequate time to discuss the various proposals and give the pupils the opportunity to make their proposals.

Pic 40: The weight of plasticine

In the task itself, pupils are guided to make predictions about which of the four situations will allow them to find out which piece of plasticine is larger (heavier). The predictions are recorded and substantiated by the results of the research from the previous task. They then verify the predictions. In order to check whether they have actually obtained a relevant result by comparison, they need to use a true-false test, i. find out which of the two pieces of plasticine is actually bigger. They can find it out usingscales, but for example by dipping plasticine into the water and comparing the amount of water that the plasticine displaces is interesting proof as well. Upon observation, the teacher guides the pupils to formulate a conclusion indicating how the weight of the two objects can be compared using the swing.