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.
Tyngdekraften bestemmes av et objekts masse. Tyngdekraften mellom to objekter er proporsjonal med objektenes masse, og den avtar svært raskt så snart vi skiller dem fra hverandre. Faktisk tiltrekker vi også objekter med ‘vår’ tyngdekraft, men vi er for lette til å kunne se virkningene! Solen er imidlertid så stor at den klarer å holde oss nær seg selv om den er så langt unna. Månen utøver også sin tyngdekraft; siden den er mindre og lettere enn Jorden, ville vi, hvis vi kunne veie oss på den, oppdage at vi veier omtrent en sjettedel av det vi veier på Jorden.
Man kan spørre seg hvorfor månen ikke faller ned på jorden, slik et eple faller fra treet. Årsaken er at månen aldri står stille. Den beveger seg hele tiden rundt oss. Uten tyngdekraften fra Jorden ville den bare sveve bort ut i verdensrommet. Denne kombinasjonen av hastighet og avstand fra Jorden gjør at Månen alltid befinner seg i balanse mellom å falle og å rømme. Hvis den var raskere, ville den rømme; var den noe tregere, ville den falle!
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!
