Chapter 1 Introduction Conceptual Questions Solutions

Atomic clocks are based on the electromagnetic waves that atoms emit. Also, pulsars are highly regular astronomical
clocks.
4.
(a)
(b)
(c)
6.
Let us assume the atoms are solid spheres of diameter 10−10 m. Then, the volume of each atom is of the order of
10−30 m3. (More precisely, volume = .) Therefore, since 1 cm3 = 10−6 m3, the number of atoms in the
solid is on the order of 10−6/10−30 = 1024 atoms. A more precise calculation would require knowledge of the density
of the solid and the mass of each atom. However, our estimate agrees with the more precise calculation to within a
factor of 10.
8.
Realistically, the only lengths you might be able to verify are the length of a football field and the length of a
housefly. The only time intervals subject to verification would be the length of a day and the time between normal
heartbeats.
10.
In the metric system, units differ by powers of ten, so it’s very easy and accurate to convert from one unit to another.
Chapter 1
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