Effervescent Launchers

1. Effervescent Launchers Vanderbilt Student Volunteers for Science Training Presentation Fall 2004

2. Important!!! • Please use this resource to reinforce your understanding of the lesson! Make sure you have read and understand the entire lesson prior to picking up the kit! • We recommend that you work through the kit with your team prior to going into the classroom. • This presentation does not contain the entire lesson—only selected experiments that may be difficult to visualize and/or understand.

3. Pre-Lesson Set-Up • Identify the best location to conduct the testing. Outside or a large tiled cafeteria floor works best. • Fill the two rinse pans half full of water and set them behind the launchers with the two waste containers. • Reserve one launcher and clean water bottle near the instructor for the demo. • Make sure all launchers are assembled and set for 60° (the top hole of the launcher). • Split the class into eight groups of four students each.

4. I. Introduction • Please refer to manual for detailed instructions and explanations • Projectile motion • Launch angles and launch force. • Alka-seltzer and water are used as fuel for launcher. When mixed, these ingredients produce a gas (CO2) that provides the launch force.

5. II. Set-Up and Demonstration • Film Canister Demo • Do not do this demo directly underneath a fluorescent light. • Show students the bag with the ¼ size Alka-Seltzer tablet. • Place the film canister where the students can easily see it and empty the Alka-Seltzer bag into the canister. • Using a syringe, add 10 mL of water to the canister and quickly replace the lid.

6. II. Set-Up and Demonstration • Show the launcher and how to vary the angles • Four holes represent different angles (60°, 45°, 30°, 20° ) • Insert canister into pocket • The thumbscrew should only be loosely tightened.

7. III. Identifying the Best Angle for Maximum Distance of the Projectile • Set the launcher to the correct angle (60° first). • Place the canister with the lid removed in the pocket. Do not tighten the thumbscrew. It should only loosely hold the canister in place. • Set the launcher firmly on the ground in the correct direction.

8. III. Identifying the Best Angle for Maximum Distance of the Projectile • Make sure that the film canister is clean and dry before each trial! • Students need to wear goggles during testing, but may remove them with permission of the instructor during the measuring parts of the test

9. III. Identifying the Best Angle for Maximum Distance of the Projectile • Put a ½ piece of Alka-Seltzer table into the canister. • Measure 10 ml into the syringe from the clean water bottle. • Only two group members should be near the launcher. All others should be behind the launcher.

10. III. Identifying the Best Angle for Maximum Distance of the Projectile • Together, one member should add the water to the canister while the other member quickly places the lid tightly on the canister. • Both should then move behind the launcher. One member will hold the launcher at the base from behind to prevent recoil or tipping of the launcher. • After all launchers have fired, one group member should place a marker at the landing spot and retrieve the lid. Another group member should take the canister and pour the liquid into the waste container. Then the canister should be rinsed in the rinse pan and completely dried. Replace the canister into the launcher. The lids do not need to be rinsed between trials. • Repeat the procedure, but all group members should perform a different task. • After the second trial, two group members can measure and record on the data sheet both distances, while the remaining members change the launch angle and rinse the canister. • Conduct two trials for each angle and record all the distances. • Take an average of the two trial distances as the distance for that angle.

11. IV. Discussion of Students’ Results • Ask each group what launch angle provided the maximum distance and how far the rocket flew on average from that launch angle. • Discuss any variations between the groups’ results.