Science and Technology K–6 · Year 4

Parachute drop: a bigger canopy falls slower

Science understanding: Physical sciences

Practical, model not builtLow risk

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The idea

Air resistance is a force that pushes against a falling object, and a larger canopy meets more air, so the same load reaches a lower steady speed and takes longer to fall.

Safety card

Low riskAn adult supervises

Hazards

drop from a height
plastic bags

Controls

an adult drops from the ladder or balcony
learners stand clear
no bags over heads

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

What you need

3 plastic-bag canopies cut as circles of 20, 30 and 40 cm diameter
8 lengths of cotton thread 30 cm each per canopy
a 10 g load per parachute (a washer or plasticine ball, weighed)
tape, hole punch
a safe 2.0 m or higher drop point and a stopwatch

How to do it

Attach eight threads evenly around each canopy and tie them to the 10 g load.
Drop each parachute from the same height with the canopy opened by hand, timing from release to landing. Do five drops each and record every time.
Work out the mean time and the average speed (height divided by time) for each canopy.
Graph fall time against canopy diameter.
Double the load to 20 g on the 30 cm canopy and record how the time changes.
Compare with the model's predicted terminal speed for each canopy.

What you should see

Fall time rises with canopy size and drops when the load doubles. For a 10 g load under a 30 cm canopy (area 0.0707 square metres) with drag coefficient 1.4 and air density 1.2 kg per cubic metre, the terminal speed is 1.28 m/s, so 2.0 m takes about 1.6 s once at speed; the 20 cm canopy gives 1.93 m/s and the 40 cm canopy 0.96 m/s. Stepping the model from rest adds the first fraction of a second spent speeding up: 1.65 s for the 30 cm canopy, 1.17 s for 20 cm, 2.14 s for 40 cm, and 1.23 s for the 30 cm canopy with 20 g. Real drops run faster than the model when the canopy does not open fully, because the open canopy spans less than its flat cut diameter, and because the canopy's own mass adds to the load.

What changes

What you change: canopy diameter
What you measure: fall time from 2.0 m
What you keep the same: load mass
thread length
drop height
release method

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Parachutes work by trapping air like a bag (they work by pushing air out of the way, which pushes back).
A bigger parachute falls slower because it is heavier.
Air is nothing, so it cannot push.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST2-9PW-ST ST2-1WS-S
Australian Curriculum v9AC9S4U03AC9S4I02AC9S4I03AC9S4I04

Sources

The pages the author read to write this activity.

All Concept Studio activities