Part of the show Cambridge Science Festival - Xenova's Anti-Smoking Vaccine
Why don't rockets leave big holes in the ground when they launch ?
When the rocket motors ignite, huge amounts of hot gas are forced from the back of the rocket. As the famous Cambridge physicist Isaac Newton observed in his 3rd law of motion, for every action there is an equal and opposite reaction, meaning that in the context of the rocket, the hot gas coming out of the back exerts the same force on the rocket, but in the opposite direction, pushing it forwards. The rocket isn't actually pushing on the ground to make it go along and although it doesn't produce big holes in the ground, things can get a bit scorched !