Balloon Rockets: Practical investigation
Aim: Investigate Newton’s law of motion
Hypothesis: If the ballon rocket will move forward in the opposite direction to the air
then the escaping from the balloon due to the reaction force will be generated.
Materials:
● Balloon
● A length of string will span the classroom
● Drinking straw
● Scissors
● Sticky tape
● Tape measure
Risk Assessment:
Hazard Risk Precaution
The ballon could pop It could pop on someones Keep away from face when
face and hurt them blowing the balloon up
Scissors Could drop andd hurt Keep it further away from
soemone or cut someone the edge of the table.
Method
1) Tie the end of the string to a structure at the far end of the classroom. This will serve
as guide rope.
2) In groups, design a balloon rocket that when inflated will travel the greatest possible
distance along the guide rope.
3) Inflate a balloon and hold the opening closed.
4) Sticky tape a section of the drinking straw to the inflated balloon – this will fed
through start of the guide rope.
5) Take turns releasing the balloon and observe its motion through the room.
6) Use the tape measure to record the distance travelled by each group’s balloon rocket
and record the results on the board.
Results:
1. What happens to the air inside the balloon when you release the balloon?
When the balloon is released, the air inside it rushes out through the opening. This
rapid expulsion of air is due to the higher pressure inside the balloon compared to the
atmospheric pressure outside.
2. Which way does the balloon move as the balloon is released?
The balloon moves in the opposite direction to the escaping air. This is an example of
Newton's third law of motion for every action, there is an equal and opposite reaction.
3. What provides the force that pushes the balloon through the air?
The force that pushes the balloon through the air is provided by the expelled air. As
the air rushes out of the balloon, it exerts an equal and opposite force on the balloon,
propelling it forward along the guide rope.
4. Explain why it is essential to tape the section of drinking straw to the balloon and to
feed it through the string
Taping a section of drinking straw to the balloon and feeding it through the string is
essential because it ensures that the balloon travels along the guide rope. The straw
acts as a guide, keeping the balloon aligned and reducing random movements, which
helps in accurately measuring the distance traveled.
5. Compare the way that the balloon is propelled and the way a jet engine works. How
is it similar? How is it different?
Similarities:
Both the balloon and a jet engine operate based on the principle of Newton's third law
of motion. They expel matter (air in the case of the balloon, and exhaust gases in the
case of a jet engine) in one direction, which results in a thrust force that propels them
in the opposite direction.
Differences:
A balloon releases air stored under pressure in an elastic container, while a jet engine
burns fuel to create high-pressure exhaust gases.
Conclusion:
The balloon rocket experiment demonstrates Newton's third law of motion, where the
expulsion of air from the balloon creates an equal and opposite thrust, propelling the
balloon along the guide rope. This simple setup effectively illustrates the basic
principles of propulsion, similar to how jet engines operate by expelling exhaust gases
to generate thrust.
