## How to work with Newton’s Laws

The science we learn at school, including Newton’s Laws, tell us that it is impossible for Santa to deliver presents to all the children in the world! Imagine the speed he would have to fly at to travel such long distances in such a short space of time!

He would be travelling so quickly, the air resistance would be enormous. Assuming he sets off from the east, and due to the different time zones, he actually has 31 hours to complete his deliveries. To do this his sleigh needs to be moving at over 670 miles per second. That is over 3300 times the speed of sound!  Don’t forget he also has to stop regularly to drop off the presents. Rough calculations show he needs to make at least 768 visits per second! You are very unlikely to see Santa while he works, as he has only one thousandth of a second to stop his sleigh, jump down the chimney, eat his snack and leave the presents. He is one very speedy worker!

In order for this to happen (if it isn’t magic!), scientists suggest he experiences time dilation. In other words, the faster an object moves, the more time will slow down for them.  We know he travels ridiculously quickly, therefore time significantly slows down for him, giving him more time to deliver all those presents. It also means he grows old much slower than other people. Alongside time dilation, he also experiences time contraction. This suggests the faster an object moves, the smaller it gets. It would certainly explain how he can fit down the chimney with a sack of presents.

Let’s not forget how heavy his sleigh must be. Even if each child only got one tiny present, it would be ridiculously heavy. Those reindeer must be incredibly strong and able to withstand the heat resulting from the enormous air resistance. Normal reindeer would burst into flames and vaporise almost instantaneously. Santa must also be able to withstand centrifugal forces up to 17.500 times greater than gravity. Luckily for us, Santa does not obey the laws of Physics!

GCSE scientists, you need to know all about forces and motion, and be able to explain Newton’s Laws. For help with this, try our new guide, “How to work with Newton’s Laws”. The guide includes an explanation of Newton’s first, second and third Laws. As always there are questions to try, and answers to check your understanding.

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