We know that Neil Armstrong was the first person to land on the Moon. He, along with Edwin Aldrin and Michael Collins, re-entered the Earth in NASA's Apollo spacecraft.
We know that if we drop a stone from a height, the stone's speed keeps increasing. The more the height from which the stone falls, the higher its speed as it reaches the ground.
The Apollo spacecraft reached the Earth after falling hundreds of kilometres! Then, how did it land safely? Shouldn't it have crashed onto the Earth at a very high speed? We will answer this question at the end of the module.