Rocket Boat

SCIENCE CONCEPT:

The world's mightiest rockets like NASA's giant Saturn 5 work on exactly the same principle as an air-filled rubber balloon which flies around the room when you release it. They are both pushed forward by the backward rush of escaping gas. Newton's Third Law of Motion states that if an object is pushed or pulled, it will push or pull to an equal extent in the opposite direction. In a rocket, the fuel is ignited and, as it burns, generates high-pressure gas, which pushes out in all directions inside the rocket. However, when the rocket's exhaust is opened, hot gas rushes out, creating an upward thrust, and the rocket is pushed from its launch pad. You can see how exhaust gas powers a rocket by making a rocket boat.

STUDENT OBJECTIVE:

The student will explore how exhaust in a rocket boat pushing out the back will pull the boat forward, just as Newton's Third Law of Motion states.

OVERVIEW:

In this activity, the student will build a rocket boat and observe the dynamic of Newton's Third Law of Motion in action. You will need an aluminum cigar tube, nail, hammer, pipe cleaners, glue, water, candle stubs and an aluminum food tray.

PREPARATION TIME:

20 minutes.

LESSON TIME:

40 minutes.

TEACHER PREP:

Gather the materials that you will need for the experiment. Suggestion: That you do this experiment with the students. You will need the following items for the experiment: one aluminum cigar tube, one nail, one hammer, two pipe cleaners, glue, water, three candle stubs, and an aluminum food tray.

WORDS TO KNOW:

pulling

pushing

opposite

ignited

high-pressure gas

exhaust

upward thrust

TEACHER TEXT:

Physics is the study of the natural phenomena of the universe, including the properties of energy, matter, light, gravity, and magnetism. The Laws of Physics are always in ^„motion'. There is motion everywhere around us. Even if you think you are being perfectly still, you are moving in some small way. Why do you keep moving even after the car you're riding in comes to a sudden stop? Newton was fascinated by the things that he observed around him and never grew tired of exploring new possibilities.

The real world is far more interesting because it is filled with moving things. You are a vibrant part of this motion-filled world. If you could look inside your body, you would find your heart pumping about once each second, sending blood rushing into arteries that swell with each beat and then contract, forcing the blood outward to all parts of your body.

Just as you are filled with motion from within, you are surrounded by motion on the outside. You can see birds and airplanes moving through the air above the earth. Many fast-moving things are so far away that they appear to move slowly. Clouds driven by a strong wind often seem to be nearly motionless. An airplane traveling at 600 miles an hour appears to be moving with stately slowness when high in the sky. The earth travels through space at even greater speeds, and yet you are unaware of its motion.

Are all moving objects pulled or pushed along by forces? These questions have been asked for thousands of years. Sir Isaac Newton investigated these questions and discovered the Laws of Motion and the Universal Law of Gravitation. In the following experiment your students will discover firsthand Newton's Third Law of Motion.

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Last modified: Tue Mar 24 16:46:50 PST 1998