Speed changes only when which event occurs?

Speed changes only when which event occurs?

• A. The wave travels from one medium to a different medium
• B. The temperature changes
• C. The pressure changes
• D. The observer changes position

Answer: (A)

Speed of a wave is determined by the material it travels through. In a single, uniform medium, that speed stays the same. When the wave crosses into a different medium, the properties that set that speed change, so the wave must speed up or slow down at the boundary. Temperature or pressure can alter speed within a given medium, but the definitive change occurs when the wave enters a different medium. An observer changing position doesn’t change the wave’s intrinsic speed; it just affects how we perceive or measure the motion.

Speed of a wave is determined by the material it travels through. In a single, uniform medium, that speed stays the same. When the wave crosses into a different medium, the properties that set that speed change, so the wave must speed up or slow down at the boundary. Temperature or pressure can alter speed within a given medium, but the definitive change occurs when the wave enters a different medium. An observer changing position doesn’t change the wave’s intrinsic speed; it just affects how we perceive or measure the motion.