Shooting Stuff

Most recent answer: 10/22/2007

Why does steam, escaping from a hole in a metal tube, attached to an object, propel that object?
- Danny Jodoin (age 10)
Grande Prairie, Alberta
Hi Danny,

Steam is just water that has turned into a gas. The steam takes up a lot more space than just water. When all that steam is stuck in a tube, it tries to find a way out. As more and more water becomes steam, the pressure in the tube gets higher. If there is something plugged in a hole in the tube, the steam will push so hard that the object is shot out. Once the object is gone, the steam can spread out everywhere. As the steam is forced out in one direction, Newtons 3rd law says that an equal force, in the opposite direction, is applied by the escaping steam on whatever the object is...that’s why it moves.


(published on 10/22/2007)