9. Using v = f λ, we find the length of one cycle of the wave is λ = 350/500 = 0.700 m = 700 mm. From

f = 1/T , we find the time for one cycle of oscillation is T = 1/500 = 2.00

× 10

−3

s = 2.00 ms.

(a) A cycle is equivalent to 2π radians, so that π/3 rad corresponds to one-sixth of a cycle. The

corresponding length, therefore, is λ/6 = 700/6 = 117 mm.

(b) The interval 1.00 ms is half of T and thus corresponds to half of one cycle, or half of 2π rad. Thus,

the phase difference is (1/2)2π = π rad.