Square Friction Cube With Hook, 4 Surfaces, 2 Inch, Provides Four Surfaces For Exploration Into The Force Of Friction. Each Side Of The 2in Cube Provides A Surface (Wood, Paper, Vinyl, Sandpaper) With A Different Coefficient Of Friction
Ring And Ball, Mounted On Separate Handle Ball, Dia. 22mm, Consists Of A Brass Ball And A Brass Ring, Each Individually Mounted On Brass Rods With Wooden Handles.