Activitiy 1.2 - Disability Aids

Using their knowledge of physics, the pupils should be able to explain how/why some disability aids function and which movements are made easier or possible.

Biology, physics and technology

Everyday aids for disabled people. Products of various types to assist in everyday tasks such as eating and drinking, getting dressed or opening packages; these can be bought in a shop or on the internet. Make available too some different packages that can be difficult to open, for example plastic bottles, glass jars or tins of food and some paper cartons. It is important to use real packages so that the pupils can test them and understand for themselves the functions and describe the physics behind the activity with their own words.

Divide the class in groups of 3-4 pupils. The task is in three parts.

The first part is about the disability aids
The second part is about opening a common package
The third part is about describing the underlying physical principles

Distribute to each group some aids for people with decreased motor skills. The pictures show examples of some aids that can be used:

Ask the pupils to explain what they are and what they are to be used for. What functions do they have? Explain how movement occurs!

After this, each group is given a common package to open. The task is to discover how a person with reduced hand strength can open the package with the help of one or other of the objects. Examples of the packages that can be used are:

To conclude the Activity, the pupils are asked to explain and demonstrate the principles for increased hand strength. Theoretically, most cases concern turning around a fixed point. What is to be noticed is that the force used does not work directly at the point at which the result is desired but at some distance from it. The result is dependent upon the degree of force and the distance between the force and the point where the result takes place. This distance is called torque or leverage and is measured at right angles to the force. Note that torque also has a direction – one can turn clockwise or anti-clockwise. This is, therefore, the same principle one uses when a pole or bar is used to lift a stone from a hollow in the ground. The pole functions as a lever; see picture.

Note that the lever always has a fixed point around which the turn occurs.

Using a lever is a discovery made in ancient times and is counted – together with the sloping plane, the wedge, the screw and the wheel – amongst the most simple machines. It can be interesting to know that scientists and philosophers in ancient times speculated a great deal about the properties of these simple machines and their use in increasing force.

In order to demonstrate the idea of a lever, you can do the following: Open a door only about 10cm wide and try pressing against the door close to the hinge. Note the amount of force required to open the door further. Then try pressing against the edge of the door and compare how much force is required in these two situations. When is least force required? The correct answer is, that least force is required when one presses against the edge of the door. The lever in this case is the complete breadth of the door.