Question

A jet aeroplane is flying at supersonic speed. When the sound of the jet appears to be coming vertically downwards, the angle of sight of the aeroplane with the horizontal cannot be

• A. ${60}^{\circ }$
• B. ${40}^{\circ }$
• C. ${30}^{\circ }$
• D. ${25}^{\circ }$

Answer 1

Answer: (A)

${60}^{\circ }$

Since the jet is moving at supersonic speed, $v\ge c$. Thus the angle that the velocity of sound relative to the observer forms with the horizontal is less than or equal to ${45}^{\circ }$.