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Balloon Rocket Experiment

The following optional balloon rocket experiment should help you appreciate Newton’s third law better.

Experiment: Balloon Rocket

Aim

In this experiment (better done with teammates, e.g. friends or classmates), you will use a balloon rocket to investigate Newton’s third law. A fishing line will be used as a track and a plastic straw taped to the balloon will help attach the balloon to the track.

Apparatus

You will need the following items for this experiment:

  1. balloons (one for each team)

  2. plastic straws (one for each team)

  3. tape (cellophane or masking)

  4. fishing line, \(\text{10}\) metres in length

  5. a stopwatch – optional (a cell phone can also be used)

  6. a measuring tape – optional

Method

  1. Divide into groups of at least five.

  2. Attach one end of the fishing line to the blackboard with tape. Have one teammate hold the other end of the fishing line so that it is taut and roughly horizontal. The line must be held steady and must not be moved up or down during the experiment.

  3. Have one teammate blow up a balloon and hold it shut with his or her fingers. Have another teammate tape the straw along the side of the balloon. Thread the fishing line through the straw and hold the balloon at the far end of the line.

  4. Let go of the rocket and observe how the rocket moves forward.

  5. Optionally, the rockets of each group can be timed to determine a winner of the fastest rocket.

    1. Assign one teammate to time the event. The balloon should be let go when the time keeper yells “Go!” Observe how your rocket moves toward the blackboard.

    2. Have another teammate stand right next to the blackboard and yell “Stop!” when the rocket hits its target. If the balloon does not make it all the way to the blackboard, “Stop!” should be called when the balloon stops moving. The timekeeper should record the flight time.

    3. Measure the exact distance the rocket travelled. Calculate the average speed at which the balloon travelled. To do this, divide the distance travelled by the time the balloon was “in flight.” Fill in your results for Trial 1 in the Table below.

    4. Each team should conduct two more races and complete the sections in the Table for Trials 2 and 3. Then calculate the average speed for the three trials to determine your team’s race entry time.

Results

 

Distance (m)

Time (s)

Speed (\(\text{m·s$^{-1}$}\))

Trial 1

   

Trial 2

   

Trial 3

   
  

Average:

 

Conclusions

The winner of this race is the team with the fastest average balloon speed.

Optional Video: Balloon Rocket Demonstration

While doing the experiment, you should think about,

  1. What made your rocket move?

  2. How is Newton’s third law of Motion demonstrated by this activity?

  3. Draw pictures using labelled arrows to show the forces acting on the inside of the balloon before it was released and after it was released.

Optional Video: Apollo 8 Saturn V Rocket Launch

The Saturn V (pronounced “Saturn Five”) was an American human-rated expendable rocket used by NASA’s Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fuelled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload. It remains the tallest, heaviest, and most powerful rocket ever brought to operational status and still holds the record for the heaviest launch vehicle payload.

Optional Video: How a Rocket Works – From Earth to Space

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