Hurrah, we come to the end of the module! We started by asking how the Apollo spacecraft reached the Earth safely even though it fell hundreds of kilometres. The answer is Air Drag, or friction to due to the Earth's atmosphere.

We learnt that friction slows down moving objects. It is this friction due to the Earth's atmosphere that reduced the speed of the Apollo spacecraft.

Otherwise, by the time Apollo reached the Earth, it would be travelling at thousands of kilometres per hour. It would have crashed onto the Earth!