What would happen if an aspiring villain, a scientist who’s a little too old and deaf, and a group of clumsy and spiteful assistants ventured into the construction of rockets and anti-gravitational weapons? You can find out in Despicable Me, Universal Pictures’ 3D animated feature coming out in cinemas on 15 October. In the film, our odd heroes struggle with the Moon, its mass, and the force of gravity.
So let’s just have a little talk about these key concepts in order to understand better what happens in the film. Have you ever seen a fruit or object falling from a tree? And have you ever tried to throw a stone and watch it fall? This force that ‘brings down’ things is called the force of gravity.
We are constantly attracted to the Earth by its gravitational force , That is the reason why we always keep our feet on the ground. We don’t need to be in direct contact with Earth to be attracted by it however; not being too far away is just enough for the same forces to act. This is why our own planet orbits around the Sun, and the Moon orbits around the Earth.
Gravitationskraften bestäms av ett objekts massa. Gravitationskraften mellan två objekt är proportionell mot objektens massa och avtar mycket snabbt så fort vi separerar dem. I själva verket drar vi också till oss objekt med ‘vår’ gravitationskraft, men vi är alldeles för lätta för att kunna märka effekterna! Solen är dock så stor att den kan hålla oss nära sig även när den befinner sig så långt bort. Månen utövar också sin gravitationskraft; eftersom den är mindre och lättare än jorden skulle vi, om vi kunde väga oss på den, upptäcka att vi väger ungefär en sjättedel av vår vikt på jorden.
Man kan undra varför månen inte faller ner på jorden precis som ett äpple från ett träd. Anledningen är att månen aldrig står stilla. Den rör sig ständigt runt oss. Utan jordens gravitation skulle den bara sväva iväg ut i rymden. Denna kombination av hastighet och avstånd från jorden gör att månen alltid befinner sig i balans mellan att falla och att fly. Om den var snabbare skulle den fly; var den något långsammare skulle den falla!
We said the force of gravity depends on distance too. If we were to distance ourselves enough, we could escape its hold. That’s what we try to do with spacecraft. We need to reach and exceed the so-called ‘escape velocity’, that is about 11.2 km/s (at such velocity, we would be able to move from London to New York in just ten minutes!). Once a shuttle reaches this velocity, it is free to travel in the Solar System.
Inside an orbiting shuttle we do not feel the gravitational force of the Earth. Objects don’t fall, they float; if you jump up, you don’t come back down. A similar thing also happens to astronauts when they are in space stations orbiting the Earth.
In Despicable Me you will see rockets flying and the effects of gravity on the Moon. Gru has a group of assistants called Minions who will help him in his quest to steal the Moon and become the most famous villain in the world. We hope you enjoy the film!
