How does the amount of water or surface roughness affect how much friction there is between a blade and the ice surface?
Freeze water in a rectangular pan.
Try dragging a brick across the ice, using a spring scale to measure the amount of force needed.
What combination of water and ice produces the least resistance?
Which produces the most?
Ever since the Egyptians first built the pyramids, people have been looking for ways to reduce friction.
Today, many super lubricants exist for specialized purposes.
Research some of these products and explain why each can work under certain conditions.
Research how sail designs for boats have changed over time.
What were some of the disadvantages of old-fashioned square riggers compared to modern vessels?
Why do racing yachts have three or four different sails?
What purpose does each one serve?