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and check your answers to Exercise 8c.

Narrator: That day, Stapp was subjected to extremes of force beyond the imagination. When the
sled's rockets fired, he shot from zero to over 1.000 kilometres per hour in just three seconds,
subjecting him to 20 Gs. When the sled hit the pool of water in the braking zone, it was like
hitting a brick wall. Stapp slowed from the speed of a bullet to a complete stop in little more than
a single second. Incredibly, John Stapp survived the ride, although so much blood had rushed
into his eyes that he was unable to see for some time afterwards. Before the test, doctors had
believed that human beings were incapable of surviving forces greater than 17 Gs. When the
sled hit the water, Stapp had pulled a crushing 46 Gs.

e Complete the following groups of synonyms using the words in the box.
able to; capable of; cope with; exceed; incapable of; intended for;
subjected to; surpass; unable to; withstand;
1 exposed to (a force) / subjected to
2 resist (a force) / /
3 go beyond (a limit) / /
4 suitable for (a use) /
5 can / /
6 can’t / /

f Complete the following sentences about Sonic Wind using the correct form of the words
in Exercise 8e.
1 The bolts fixing the camera to the sled had to cope with high shear forces.
2 The sled’s rockets were generating enormous thrust.
3 The pools at the end of the track were stop the sled rapidly.
4 The skids on the sled had to high levels of friction.
5 At full speed, John Stapp was several tonnes of air pressure.
6 The rear of the sled was resist the shock of deceleration, and broke
off.
7 Doctors thought people were surviving forces of 17 Gs and above.
8 John Stapp the 17 G limit by a huge margin.

9a You are a consultant engineer and your firm have received an email from an
entrepreneur with an ambitious plan. Read the following email extract and note the key
information.

b In pairs, discuss the key information in Exercise 9a and consider the following points.
• the level of G force
• a safe length for the track
• the feasibility of using wheels
• the suitability of the braking systems suggested

c ► 10.6 Jasmine and Andrew, consulting engineers, are discussing the issues in Exercise
9b. Listen and compare what they say with your ideas from Exercise 9b.

Jasmine: I think what he’s suggesting in terms of acceleration and deceleration forces is
reasonable.
Andrew: Yeah. 2 G sounds about right. Anything less than that, and the track length’s going to
exceed the size of the site. And if you start getting close to 3 G, or beyond that, then that's
probably going to be a bit too much for the average passenger.

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