Chapter 17
3. (a) The time for the sound to travel from the kicker to a spectator is given by
d
/
v
, where
d
is the
distance and
v
is the speed of sound. The time for light to travel the same distance is given by
d
/
c
, where
c
is the speed of light. The delay between seeing and hearing the kick is
Δ
t
= (
d
/
v
) – (
d
/
c
). The speed of
light is so much greater than the speed of sound that the delay can be approximated by
Δ
t
=
d
/
v
. This
means
d
=
v
Δ
t
. The distance from the kicker to spectator
A
is
d
A
=
v
Δ
t
A
= (343 m/s)(0.23 s) = 79 m.
(b) The distance from the kicker to spectator
B
is
d
B
=
v
Δ
t
B
= (343 m/s)(0.12 s) = 41 m.
(c) Lines from the kicker to each spectator and from one spectator to the other form a right triangle with
the line joining the spectators as the hypotenuse, so the distance between the spectators is
(
)
(
)
2
2
2
2
79m
41m
89m
A
B
D
d
d
=
+
=
+
=
.
10. (a) The amplitude of a sinusoidal wave is the numerical coefficient of the sine (or cosine) function:
p
m
= 1.50 Pa.
(b) We identify
k
= 0.9
π
and
ω
= 315
π
(in SI units), which leads to
f
=
ω
/2
π
= 158 Hz.
(c) We also obtain
λ
= 2
π
/
k
= 2.22 m.
(d) The speed of the wave is
v
=
ω
/
k
= 350 m/s.

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*