Turbulence

In this task you want to use you phone to document your investigation

Place a few millimetres depth of water into a white saucer. Add a drop or two of ink at the water’s edge without disturbing the surface too much. Drag the tip of a needle slowly from the ink spot across the saucer, as shown in the figure.

Describe the effect on the ink spot.

Repeat the experiment, dragging the needle tip rapidly across the saucer. Describe the effect on the ink spot.

Try both tests again with a microscope slide edge on, dragged slowly and then rapidly, as shown in the figure. What does this demonstrate?