Ask your students to work in groups of 3 or 4 each. Each of the groups must make a list of 7-10 examples of simple machines around them. Each of the machines should include the following description :
- Name of the device
- The job that is made simpler
- The simple machine(s) used, as understood by the students.
- Any suggestions for changes that might make the machine better.
At the end of the activity, you can discuss some of the nice ones in the class.
Explain to your students how simple machines work by introducing the concept of Work as follows :
Simple machines seem to be doing some magic as they help us do things with lesser effort. But infact, there is a trade off - by decreasing the effort to complete the task, we are infact applying the effort over a greater distance.
Completing a task requires work. The work done in a task is a product of the force(effort) and the displacement(distance). The work for a task remains the same or, constant, by whichever method we do it. So, if we decrease the effort we must apply it over a greater distance so that their product, the work, remains constant.
Define and explain M.A. as follows
The decrease in the required effort is expressed in numbers by the term Mechanical Advantage. It is given by 'the load moved divided by the effort applied'.
For example, for the simple pulley shown in the demonstration, the mechanical advantage is 1 since the weight lifted is equal to the force applied. Also show them the M.A. of the lever you had shown.
Here is a crossword puzzle on Simple Machines. Print out and ask the students to work on it in pairs. Give them 15 minutes to do it.
