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.