FlightWALT-Develop an understanding ofrocket propulsion.
1. Aimexplain how rocket propulsion works in terms of gases beingpushed out one end so that a force is exerted on the rocket inthe opposite directioncarry out a fair test to find the amount of vinegar that makesthe rocket go the highestexplain that pressure needs to build up inside the film canisterfor a successful launchexplain how the speed of the rocket changes as it goes up andcomes back down and how these changes are related to theforces acting on it.
2. PriorKnowledgeWhat do I know about thistopic already, or what do Ithink is going to happen?
Momentum &GravityOnce the lid has come off the rocket and therocket is moving upwards, its momentum willkeep it moving upwards.The force of gravity acts on the rocket andpulls it back towards the Earth. This forceremains the same throughout the flight andmakes the rocket slow down, momentarilystop and then keep speeding up as it falls backdown.
Each groupwill needwill needA white film canister for each pair ofstudents• ∆αµπ baking soda• White vinegar• Coloured card- scissors, ruler, tape• Vivid• Spoon•Παπερ τοωελσ
The ChallengeTo make a film canister into a rocket andto find out how to make it fly as high aspossible – a well made rocket will flyabout twice as high as the classroom.
continuedThere will be a competition to see whichrocket flies the highest, which has thenicest flight and which is the bestlooking.
VariablesThings to keep the same – nose cone,fins and amount of baking soda placed inthe lid.The one variable to change – amount ofvinegar.The one thing to measure as a result –height reached by the film canister.Work in groups of two to make yourrockets.
Making your rocket-the noseTo build the nose cone, draw a circle about twicethe diameter of the film canister onto a piece ofcoloured card.Cut to the exact centre and then curve the cardaround on itself to make a cone.Tape this to the closed end of the canister.
Making your rocket-the fins.To make fins, cut 3 or 4 equal sized trianglesfrom the coloured card.Tape them evenly spaced to the open end of thefilm canister. (For four fins, use the 3, 6, 9 and12 o’clock positions. For three fins, use 4, 8 and12 o’clock positions.)Make sure tape and fins still allow the lid to sealproperly.
Making your rocketDraw marks at 1 cm intervals on theoutside of the canister measuring fromthe closed end.These are the guides for filling withvinegar for each trial.
Launching your rocket-step 1.Fill the indent in the lid with baking soda– level it off with a spoon or finger sothere is the same amount used for eachlaunch. Make sure the edges of the lidand the canister are wiped clean sothere are no leaks at launch time.
Launching your rocket-step 2.Start with 1 cm of vinegar in the canister. Onceat the launch site, hold the canister firmly in onehand and use the palm of your other hand tosnap the lid closed, being careful to keep holdingthe rocket vertically upside down so that thevinegar and baking soda don’t mix.
Launching your rocket-step 3.Turn the rocket over, give it a brief shake, placeit on the ground and step well back.If the rocket does not launch after about 20seconds, carefully approach from a low side-onstance and give it another quick shake. If youcan see bubbles and liquid escaping from thecanister, it is possible that the lid was notcleaned well enough to seal or that it is broken.
Launching your rocket-step 4.Rinse out the rocket and repeat for 2 and 3 cmof vinegar. Clean the edges of the lid wellbetween launches.
Testingone (cm) white vinegar record resultstwo (cm) white vinegar record resultsthree (cm) white vinegar record results
3. ResultsHeights could be recorded in your booklet as acomparison with other objects- such as twice theheight of the classroom or estimated in metres.
Group ChallengeSelect the amount of white vinegar thatforces the rocket the highest into the air.Select one student from your group tocompete in this competition.
DiscussionQuestionsWho was expecting more vinegar tomake it go higher?What amount of vinegar worked best?Why do you think that amount workedbest?
4. Conclusion- Whatwas happening?The chemical reaction between bakingsoda and vinegar produces carbondioxide gas.When the lid of the film canister issealed, pressure builds up inside thecanister until the lid pops off and therocket is launched upwards.
4. Newton’s third lawThis law states that, for every action, thereis an equal but opposite reaction.The action is that gases are pushed outthe bottom of the film canister rocket.The reaction is that the rocket is pushedupwards.
Did you know?If a larger pressure is able to build upinside the canister before the lid popsoff, the gases will be pushed out fasterso the rocket will be pushed upwardsfaster and will reach a greater height.What would you do next time?