What it shows
A parachute slows a fall because its wide canopy pushes against a lot of air. Bigger canopies take longer to fall with the same load, and a small hole in the top makes the fall steadier instead of swinging.
The science
Gravity pulls the load down, and the air pushes up on the underside of the canopy as it falls. The bigger the canopy, the more air it has to push out of the way each second, so the upward push is larger and the parachute soon reaches a slow steady speed. A smaller canopy gives less air resistance and the load falls faster. Air spilling unevenly from under the edge makes a parachute swing from side to side; a small hole at the top lets air escape smoothly through the middle and the descent becomes steadier.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Old thin plastic bags or a cut-open polythene sheet (free)
- Thread or thin string, about 4 pieces of 30 cm per parachute
- A small toy, a bottle cap of coins or a paper cup as the load
- Scissors, tape and a ruler
- A stopwatch and a safe high place like a first-floor balcony with an adult
Safety
For this project: Drop only from a balcony or stair with an adult present, never lean over a railing, and keep plastic bags away from young children.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Cut three squares from the plastic bag, with sides of 20 cm, 30 cm and 40 cm.
Tape a 30 cm thread to each corner of every square.
Tie the four threads of each parachute to the same load, such as a bottle cap with three coins taped inside.
Hold the smallest parachute by the centre of the canopy, drop it from a measured height and time the fall to the ground.
Repeat three times and take the average, then do the same for the medium and large canopies.
Cut a small hole about 2 cm across in the centre of the large canopy and time it again, watching whether it swings less.
Make a table of canopy size against fall time and draw a bar chart.
Write down which parachute would be safest for a toy and why, using the words air resistance and gravity.
What you should see
The 40 cm canopy falls slowest and the 20 cm one fastest, with the same load. The parachute with a hole in the top falls straighter with less swinging.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Why does a parachute slow a fall?
Its wide canopy has to push a lot of air out of the way, and that air pushes back up against the fall.
2What happens with a bigger canopy?
More air resistance, so a slower fall.
3Why cut a hole in the top?
Air escapes smoothly through the middle, so the parachute does not swing from side to side.
4Would a parachute work on the Moon?
No, there is no air on the Moon to push against the canopy.
Take it further
Keep the canopy the same and change the load, then draw a graph of fall time against the number of coins.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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