Experimenting with Forces: Building & Launching an Air-Powered-Pop-Bottle-Rocket
Please download and print the illustrated child-friendly instructions with information about Materials, Tools, Assembly, Experiments. Also, you'll need to print onto A4 paper the rocket fins & nose template:
MATERIALS: Scissors, masking tape, 2 litre pop bottle (empty!), 2.2cm diameter pvc pip cut to approx 30cm length, 1 sheet of A4 paper, 1 sheet printed with nose cone and fins, felt tips or coloured pencils (if you wish to decorate your rocket).
ASSEMBLY: Follow the 10 simple steps on the 'Rocket Building Instructions' above.
LAUNCHING EXPERIMENT: Put the bottle underneath your arm with the rocket pointing forward rather than upwards. Squeeze like you are playing the bagpipes and see how far your rocket will fly! Compressed air forced from the bottle pushes the rocket forward. You can experiment with different bottles to adjust the thrust power of your rocket, you can adjust shape and size of fins and nose cones to test for drag, and add to the body rocket to test for weight and how this has an impact on lift!!
FORCE FACTOIDS = WHAT IS A FORCE
A force is basically a push or pull that causes an object to undergo a change in speed, a change in direction or a change in shape. A force has both magnitude (size) and direction.
THE FOUR FORCES WHICH HAVE AN AFFECT ON HOW THINGS FLY
WEIGHT is the force of gravity. It acts in a downward direction - towards the centre of the Earth!
LIFT is the force that acts at a right angle to the direction of motion through the air. Lift is created by differences in air pressure.
THRUST is the force that propels a flying machine in the direction of motion. Engines produce thrust.
DRAG is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure.
ALL 4 FORCES ACT ON AN AEROPLANE
When an aeroplane is flying straight and level at a constant speed, the lift it produces balances its weight, and the thrust it produces balances its drag. However, this balance of forces changes as the aeroplane rises and descends as it speeds up and slows down and as it turns.
ONLY 2 FORCES ACT ON A SPACE ROCKET IN SPACE
A space rocket has weight, even in orbit, and uses thrust to reach space and to manoeuver. But lift and drag - both created by movement through the air - are absent in the near vaccum of space.
HUMANS WANT TO FLY LIKE BIRDS BUT CAN'T FLY!
Birds inspired humans first attempts to fly, but our progress was limited until we learned that we could not fly LIKE them. Thanks to their flight weight, great strength, and complex biological design, birds and other flying creatures can use their wings to create both lift and thrust, as well as maintain control.
IN ORDER TO FLY:
- We need to overcome our own WEIGHT - that is, the force of gravity!
- To overcome gravity, we need to create an upward force called LIFT.
- To create lift, we need to generate THRUST for forward motion.
- To keep moving, we need to overcome the resistance of the air - a force called DRAG.
If a human jumps it cannot stay in the air very long! But with the invention of the aeroplane we've created machines to do what we cannot do by attaching wings to our own bodies, using wings on an aerodynamic creation with the functions to produce lift and thrust, using wings to produce one and engines the other.
