6
10
1 0
10
=
×
×
×
×
×
d
v
    = 1 1 × 10–3 m s–1  = 1 1 mm s–1
(b) (i) At a temperature T, the thermal speed* of a copper atom of
mass M is obtained from [<(1/2) Mv2 > = (3/2) kBT ] and is thus
typically of the order of 
/
B
k T M , where kB is the Boltzmann
constant