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which complies with the following competition rules.
Water Rocket Competition
Rockets must be assembled entirely from consumer products purchased from supermarkets or
DIY stores. For safety reasons, no glass or metallic components are permitted.
Rockets will be pressurised, and anchored during pressurisation using a compressor and launch
pad provided by the organisers.
Release of the rocket will be triggered by competitors, from a distance, by rope, at the moment
deemed appropriate by the competitor, based on a reading on the pressure gauge of the
compressor.

IV Discussing causes and effects

12 In pairs, discuss the difference between cause and effect in each of the following
situations.
1 a vehicle tyre overheating
2 an electrical circuit overloading
3 a ship’s hull corroding

13 a Read the title of the article in Exercise 1 3b and explain what you think it means.
b Read the article and answer the following questions.
1 What are chicken cannons designed to do?
2 Why was a chicken cannon used for a train test?
3 What were the effects of the test?

CHICKEN CANNON GOOF MAKES TECH EGGHEADS LOOK LIKE TURKEYS
When new aircraft are developed, jet engines and cockpit windshields are tested to simulate bird
strikes (mid-air collisions with birds), which can result in damage. The tests are carried out using
special compressed-air cannons that fire dead chickens. On one occasion such a gun was lent, by
an aeronautical company, to some engineers developing a new train. Bird strikes were a potential
danger, owing to the train’s high speed. Having received instructions in how to use the cannon,
the train designers bought an oven-ready chicken from a local supermarket, and subsequently
fired it at their prototype.
The effects were devastating. As a result of the impact, a hole was smashed, not just through the
windshield, but also through the back of the driver’s compartment. It was hard to believe a
chicken had caused so much destruction. Consequently, the engineers contacted their
aeronautical colleagues to enquire if the problem might be due to an issue with the gun, some
sort of fault that could have caused it to exceed its normal firing power. No malfunctions were
found. However, it was later discovered that the unexpected damage had occurred because of a
temperature issue.

c The text in Exercise 1 3b is an urban legend (or urban myth) - a commonly told story
that is said to be true, but which is not. Can you guess what temperature issue caused the
unexpected effects?
d Complete the following sentences using the words and phrases in the box.

because of (x2); caused; consequently; due to; owing to; result-in;
result of;
1 Bird strikes can result- in damage to aircraft.
2 Bird strikes were a potential problem for the train, /
/ its speed.
3 During the test, the train was severely damaged as a the impact.

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