Newton's Law of Gravitation
Earth and Space

No atmosphere no gravity?

Teaching Guidance for 11-14 Supporting Physics Teaching

Gravity without an atmosphere

Wrong Track: On the Moon things just float around because there is no gravity. This is because there is no air on the Moon.

Right Lines: Gravity exists on the Moon but it is less than on the Earth because the Moon is smaller. There is no atmosphere on the Moon, but this does not affect the gravitational force in any way.

Gravity on the Moon

Thinking about the learning

A common, but incorrect, line of reasoning among pupils involves making the link between gravity and the atmosphere or air.

Thinking about the teaching

The obvious first step here is to tackle the idea that there is no gravity on the Moon. Sometimes pupils will tell you that astronauts just float around on the Moon. Is this really the case? Show some pictures or videos of the Moon landings. Agree that there is no atmosphere on the Moon and make the point that this has no effect on the gravitational force.

Newton's Law of Gravitation
is expressed by the relation F=G(m_1)(m_2)/r^2
can be used to derive Kepler's First Law

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