Strawkets and Thrust
Students investigate the effect that thrust has on rocket flight. Students make two paper rockets that they can launch themselves by blowing through a drinking straw. These "strawkets" differ in diameter, enabling students to see how rockets with smaller exit nozzles provide more thrust. Students compare the distances traveled by their two strawkets after predicting where they will land. Since each student has a slightly different rocket and launching technique, they also observe which factors contribute to a strawket's thrust and performance.
Figure 1. A strawket.Copyright 2004 Gregory Vogt, Oklahoma State University for NASA Aerospace Education Services Project http://www.grc.nasa.gov/WWW/K-12/TRC/Rockets/paper_rocket.html
Engineers must know about thrust in order to design successful rockets. And, they must understand Newton's laws of motion as well as how exhaust behaves in order to calculate the thrust needed for a rocket to reach its destination. How engineers design the shapes of rocket nozzles is very important to the performance and thrust of rockets. The nozzle size and shape effects how fast the exhaust leaves the rocket as well as how much pressure it has.
After this activity, students should be able to:
- Describe thrust and what factors can affect it.
- Identify some factors that engineers must consider when designing real rockets, including safety.