Investigating the Speed of Water Waves

Investigating the Speed of Water Waves

Introduction

In this experiment I will be investigating the wave speed, of waves on

water in a tray, and how this speed is affected.

Waves can be longitudinal, when the particles move in the same

direction as the direction of the wave, or it can be transverse, when

the particles move at 90o to the direction of the wave. Water waves

are transverse waves even though transverse waves cannot travel

through liquid. This is because the waves travel on top of the water.

Aim:

The aim of this investigation is to find out how wave speed is

affected by the depth of the water. To do this we will observe whether

the depth of the water affects the wave speed of the waves in a

plastic tray.

Prediction:

I predict that the wave speed will increase as the tray is filled up

with more water. I think this because there is friction where the

water touches the tray. The deeper the water the less water touches

the tray and so the friction slows less water down. When there is less

water more of the water will be touching the tray causing more

friction and so the water will be slower. Also in previous experiments

we studied refraction. These experiments showed that when the incident

waves went past the boundary between shallow and deep water at an

angle they would change direction. This was because if the waves went

from shallow to deep, they the part of the wave that hit the boundary

between shallow and deep water at an angle first would speed up and be

faster than the rest of the wave causing the wave to travel in an

angle further from the normal line (90o to the boundary). If the wave

went...

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...slightly early or late and this would affect results. Also if

the stop clock was started late the results would be too low or early

before the tray hit the table the results would be too high and there

would be anomalous results. As the water became deeper the tray became

more full and this sometimes caused water to splash out of tray. To

stop this either the tray could be deeper or the experiment could be

stopped earlier when there was less water. Another factor that may

affect the results is if the tray was forced down instead of dropped.

This may affect the results by giving the waves more energy and

instead of just the gravitational energy and this would cause the

waves to travel faster and the results may become too low. This is why

I tried to just release the tray and not push it down during the

experiment.