Hi there, I'm trying to find a calculation to work out the speed of erosion and required rotation of water to cause erosion on a selection of 10 rocks. This is theoretical rather than an actual conducted experiment. Each rock has a density of 100 to 1000, ie rock one is 100, rock 2 is 200 etc. the amount of water in the glass is fixed. one of the rocks is placed within the glass and the water is rotated. the minimum speed that the water can be stirred to cause erosion on rock 1 is 150 on a scale of 0 - 999 when at full structural health. if the water is rotated above 200 the glass begins to crack, but as the rock begins to erode the speed that the water must be stirred increases, ie at a structural health of 75 the speed must increase to 200 and the glass damage threshold increase to 250. What equation would I use to work this out for every rock so that the scale never goes above 999 and so that as each rock is eroded the speed of erosion must increase.