Challenge :

To balance 4 similar blocks on top of each other so that they extend the furthest beyond the edge of a table

Instructions :

1. Access the website Virtual Lab Blocks and Centre of Gravity
2. In the diagram below, the blocks are labeled from the uppermost block down to the lowest block on the table, as          blocks A, B, C and D respectively.

•  To move a block, click on it and drag.
•  The status of the block(s) is indicated by its colour as explained below :
• red indicates that the block(s) have fallen
• yellow indicates that they have reached the furthest that they can go without falling
• Hint: Remember to consider the position of the line of action of the weight of the blocks through the centre of gravity (centre of mass) of the various combinations of blocks with respect to the block beneath them.
•  If you succeed in extending the blocks to the furthest possible distance from the edge of the table, the percentage reading will show 100 % along with the message:
1. When you have successfully completed, indicate to your teacher e.g. using a coloured cup.

Consider the following guidelines & hints to get at the solution or, if you had already solved it, help you understand why
your solution worked.

In the process, your group is to state a hypothesis of a possible condition for the stability of objects.
 

1. At the web site , click on the Reset button to start afresh.
2. If you click on Show c.g., the centres of gravity (in this case, the same as the centres of mass) of the different blocks  with the lines of action through them for the respective combinations of blocks are shown, as illustrated below.

1. Move block A to its furthest on the right without it falling. Can the position of the line of action of its weight through  the centre of gravity (c.g.) go beyond the edge of the lower block B ? Explain.