Teachers Note:

Description: Performing of five simple experiments to understand gravity.

Objective(s): Understand gravity through experiments and understand scientific reasoning:

• activity phase a): hypothesis
• activity phase b): experiment, observation and recording of data
• activity phase c): data analysis and conclusion

Hints:

• An object needs a certain mass and angular velocity to stay in orbit around the Earth, depending on how far it is from the Earth. For a given mass and distance from the Earth, if the angular velocity is too small, then the Earth’s gravity pulls it down, but if it is too high, the force of gravity is not strong enough to keep it in orbit around it.
• The ISS is turning around the Earth at a height of 400 kilometres and a velocity of 28.000 km/h. What would happen if it were going only at 10.000 km/h? at 100.000km/h?
• Ask the children to imagine that they perform the same five experiences in space, without the effect of the Earth’s gravity. What do they think would happen?
• You can finish this activity with a question about facts and theories: Newton is the father of the Theory of Universal Gravitation. What is the difference between a scientific fact and a scientific theory? Science is made up of many theories, but not all of them are widely accepted. Can you give an example of a scientific theory that was first predominant but was then denied by the facts? You may want to present the example when Galileo Galilei came up with the theory of the heliocentric Universe (the Sun being at the centre of the Universe). At those times, neither scientists nor the Catholic Church could to give up the former theory of Geocentricity (the Earth being at the center of the Universe). In 1633 for defending the theory of the heliocentric Universe, Galileo was put into jail where he died in 1642.

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