Answer:

Gravity as well as electrostatic and magnetic attraction and repulsion provide real life examples of forces being exerted by one object on another without them being in contact with each other. Many children are aware of magnetism and have played with fridge magnets. They may also have played with picking up small pieces of paper or other objects with a comb charged by rubbing against the sleeve of a jumper or by pulling through hair. They will also be aware that things fall towards the Earth. However, they are unlikely to think about these experiences as involving forces, i.e. pushes and pulls.

It is common for students to think that all metals are attracted by magnets, and that the size of magnets determines their strength.

Research: Fleer, Jane & Hardy (2007)

A common understanding in everyday life that dates back to ancient times is the belief that things fall towards the Earth because it is ‘natural’. Some students may use the word ‘gravity’ in this non scientific sense, i.e. without recognising that gravity involves objects experiencing a force that pulls them towards the centre of the Earth.

Students’ ideas about gravity are often linked to their ideas about the shape of the Earth and about the direction of ‘down’. Students may appear to think the Earth is a sphere but nevertheless consider, for example, that people live on a flat place either on top of the sphere or inside it.

Research: Nussbaum (1985)

This idea is also explored in the focus idea Day and night.

Some students think gravity only affects heavy objects. They don’t link weight to gravity.

This idea is also explored in the focus idea Gravity.

Explanation:

Scientific view

Scientists use the construct of a ‘field’ to explain how one object can affect another without touching it, even without any substance in between. There are three examples of such fields that we experience in everyday life:

A magnet is surrounded by a magnetic field which pushes or pulls other magnets and things made of iron, nickel or cobalt that are located within it. (Because its interior acts like a magnet, the Earth is surrounded by a magnetic field that affects things made of magnetic material, such as compasses).

A charged object is surrounded by an electric field which exerts electrical forces on other things within the field.

The Earth is surrounded by a gravitational field that pulls all other objects towards its centre.

Unlike the other two fields, which can involve both attraction and repulsion, gravity only acts by attraction. All objects attract each other by gravity, but these attractions are too weak to notice unless one object contains a huge amount of matter (stuff).