EXPERIMENT # 1: Propulsion

This experiment is one way of illustrating Newton's third law of motion (For every action, there is an equal and opposite reaction) upon which all rocket propulsion is based.

Supplies:

Modeling clay

Three short candles

Matches

Small metal tube with screw on lid (Like those used for indigestion tablets,or cigars)

The cut off bottom of a 2 liter plastic bottle (adjust height depending on candle length)

Minimum 24 round pencils or dowels

Procedure:

1. Make a small hole (off center) on the removable end of the metal tube.
2. Set candles in a row in the bottom of plastic base with clay for support.
3. Put water in the metal cylinder so it will not spill out when laid horizontally.
4. Cut notches in plastic base to support the metal tube so it rests in line with the candles.
5. Lay pencils or dowels adjacent to each other to form a platform.
6. Light the candles. This will cause the water in the tube to boil, with a jet of steam coming out of the hole. (See figures 1 and 2)

Expected Results:

The vessel will travel along the platform.

Key Concepts:

The equal and opposite reactions here are: 1) the steam from the metal tube is traveling in one direction and, 2) the "vessel" is traveling in the opposite direction.

Point out to the students that a rocket engine works on the same principal except that chemical or nuclear means are usedto make an escaping gas much like the escaping steam in the experiment.