Question

1. In a standing wave, the medium at the tip of a loop is
a) showing destructive interference
b) not moving
c) at the original amplitude of the wave
d) showing constructive interference

my answer: b

2. If a motorcycle is travelling toward an observer the frequency the observer hears is ___ the actual sound made by the motorcycle
a) greater than
b) lower than
c) smaller than
d) the same as

my answer: a