Question 1
Paper 2Easy9 marksA sound source emits a steady tone into still air. Its emitted frequency is in both situations shown in Figure 1. The figure shows successive wavefronts along the line of motion at one instant. In A, the source is fixed and O moves as indicated. In B, the source moves as indicated while O₁ and O₂ are stationary. The diagrams are schematic; compare only the separations of adjacent wavefronts.
Describe the spacing of the wavefronts in A and state whether motion of O changes their spacing in the air.
Explain whether the frequency heard by O is higher or lower than
In B, state the direction in which the source moves and compare the wavefront spacing ahead of and behind it.
State whether O₁ hears a frequency higher or lower than
State whether O₂ hears a frequency higher or lower than