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Task 3. Answer the questions to the text.
1. What is the most accurate method for measuring gravity?

2. What are the 5 main components of FG5?
3. What is the function of a dropping chamber?

4. How does the interferometer work?
5. What is the basis of the determination of gravity?
6. What is the super-spring?
7. Where can the FG5 be used?

Task 4. Define whether the following statements are true or
false and translate them. Correct the false ones according to

the text.

1. The FG5 provides unparalleled accuracy and precision.
2. The VLBI is a ballistic, or free-fall, device where the
measurement of gravity is derived by dropping an object that is

‘tracked’ in flight using an interferometer.
3. Within the super-spring, which is at vacuum, an object which
comprises a cart and a corner cube can be raised or dropped through a

distance of 20 (FG5) or 33(FG5-X) centimetres.
4. The dropping chamber is maintained at vacuum by use of an
ion pump.
5. Below the dropping chamber and central to the design of the

FG-5 is a modified Mach-Zender interferometer.
6. The Superspring provides seismic-isolation for the reference
optic to improve the noise performance of the FG5.

7. The super-spring uses a spring system with a natural period of
60minutes and is provided with oscillation dampening.
8. The measurement is directly tied to local standards, and this is

what makes the FG5 an absolute gravimeter.

II. LEXICAL EXERCISES

Task 1. Complete the sentences according to the texts above.

a) the test mass, b) environmental, c) astronomical and geodetic

grids, d) gal, e) the interference fringes, f) “Superspring”,
g) acceleration, h) falls

1. Geodetic gravimetry includes the determination of altitudes and
the treatment of ___ in connection with the special features of the

Earth’s gravitational field.
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