Movie Misconceptions 2

Time for another common movie misconception! Fans of scifi movies and TV series will recall that spacecraft always have their engine running. You might say "Well, yeah Eric, if they stop their engines, they will stop moving." This statement is completely true when considering gravity and air resistance. See, according to Newton's first law, an object won't change velocity until acted upon by another force. This means that an object in motion will not slow down until something forces it to stop. When you roll a ball on the floor, it stops rolling after a few feet, assuming it doesn't hit a wall. This ball slows down and stops due to the forces of gravity and air resistance acting on it. A spaceship is subject to the same laws of physics; however, as I pointed out in the last post, gravity and air resistance aren't present in enough force in space to make a difference.

With this knowledge, we now know that a spacecraft won't slow down or speed up if the pilot shuts off the engines. But what would really happen if the engines are run constantly? The ship would continually accelerate until something, like a planet, forced it to slow down. I personally doubt that this ship will ever reach or surpass the speed of light, but that's another post. 

Movie Misconceptions 1

In many scifi movies, large spaceships are seen as slower and less maneuverable than their smaller counterparts. (Think Star Destroyer vs. Millennium Falcon.) When you really think about it, that doesn't make sense at all. The only time a smaller ship might be more maneuver when one is on-planet; as air resistance and gravity would have less of an effect on the smaller ship. Since there is no atmosphere in space, (that's why they call it 'space'. dur hur...) there isn't any air resistance, which is what makes large aircraft and watercraft slower and less maneuverable. Without gravity and air resistance, a large spacecraft should be just as fast and maneuverable as a small one with a comparable engine. As, according to Newton's first law, a body remains in a state of constant velocity until acted upon by an outside force. In our spaceship example, air resistance and gravity are the outside forces causing the larger vessel to loose speed and maneuverability. Since these forces aren't really present in space, the larger spacecraft will not loose speed or maneuverability. Quite the opposite in fact. A larger vessel can support a larger engine/generator/power supply thing, thus meaning it gains more thrust. Without the outside forces of air resistance and gravity acting against this thrust, the larger spaceship will possess an even greater top speed than the smaller vessel.