Question

Which situations might cause two observers (A and B) to measure different frequencies for the same vibrating object? Select the two correct answers. (1 point)
Responses

Observer A is stationary and Observer B is moving.
Observer A is stationary and Observer B is moving.

Observer A and Observer B are stationary but at different distances from the vibrating object.
Observer A and Observer B are stationary but at different distances from the vibrating object.

Observer A and Observer B are both stationary and at the same distance from the object.
Observer A and Observer B are both stationary and at the same distance from the object.

Observer A and Observer B are moving at different speeds relative to each other.
Observer A and Observer B are moving at different speeds relative to each other.
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Answer 1

Select:
- Observer A is stationary and Observer B is moving.
- Observer A and Observer B are moving at different speeds relative to each other.

Reason: A moving observer experiences a Doppler shift (different measured frequency). Distance from a stationary source changes amplitude/intensity but not frequency, so stationary observers at different distances measure the same frequency.