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Presenter Greg Foot investigates what would happen if an asteroid collided with Earth. He calculates how much energy would be transferred at impact using the formula E = ½mv2 and produces an equivalent explosion to show the size of crater produced by a meteoroid the size of a golf ball. He explains why the size and speed of asteroids matters and how our atmosphere protects from all but the largest asteroids.

Greg does this by showing how air pressure alone can be used to ignite cotton wool and how air and friction cause objects smaller than 35m in diameter to burn up as they enter the Earth’s atmosphere before reaching the Earth’s surface. Unlike the Earth, the Moon has no atmosphere and this is why the Moon has a history of more numerous impacts.
First broadcast:
4 March 2012

Classroom Ideas

Students can perform simple experiments using ball bearings and a tray of sand to investigate the effect of speed and angle of impact on crater formation. This introduces the idea and use of E = ½mv2 to investigate the energy of different impacts. This can then be linked to everyday examples of collisions such as car crashes and calculations of the energy transferred at impact.

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