The frequency of the sound waves detected by a detector is exactly equal to the frequency of the sound waves emitted by a source. what can we say about the relative motion of the detector and source?

a.
both are at rest.
b.
both are moving with the same velocity.
c.
they are moving with opposite velocities.
d.
both are either at rest or moving with the same velocity.

Um vetor representa um deslocamento cujo módulo é 20 m. se v faz um ângulo de 60 graus com a horizontal, qual é o valor das componentes horizontal e vertical deste vetor?

Aforce of 9.00 newtons acts at an angle of 19.0 to the horizontal. what is its component in the horizontal direction?

Samir watches a 100-minute movie on his spaceship. maria's spaceshipe flies in the same direction as samir's spaceship but she observes his move to last 125 minutes and his spaceship to be 40 m long. how long does samir observe his own spaceship to be? according to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does marias voyage take according to samir?