Considering the nature of a water wave , describe the motion of a fishing float on the surface of a lake when a wave passes beneath the float. Is it really correct to say that the float bobs straight "up and down"? Explain.
When a wave passes beneath a fishing float on the surface of a lake, the motion of the float can be described as a combination of horizontal and vertical movements. It is not completely accurate to say that the float bobs straight "up and down" because water waves involve both oscillatory and translational motion.
The motion of a water wave consists of two main components: the crest (the highest point of the wave) and the trough (the lowest point of the wave). As the wave passes beneath the fishing float, it causes the float to move up and down vertically. This vertical motion is a result of the oscillatory motion of the wave. The float moves upward as the crest of the wave passes beneath it and moves downward as the trough passes.
However, along with the vertical motion, there is also a slight horizontal motion. This is due to the translational motion of the water wave. As the wave approaches and passes beneath the float, it carries the float forward in the direction of the wave propagation. After the wave has passed, the float moves backward slightly until it returns to its original position. This forward and backward motion is not as prominent as the vertical motion, but it is still present and contributes to the overall motion of the float.
So, when a wave passes beneath a fishing float, the float undergoes both vertical oscillatory motion and a slight horizontal translational motion. This combined motion is what gives the impression that the float bobs "up and down," although it is not strictly limited to a purely vertical movement.