Mighty Fortress Erosion Experiment (page 2)
Dry sand is like dry sugar. It piles up, but wind and water wash it away quickly, because the individual grains of sand don't stick to each other. Wet sand sticks together when combined with just the right amount of water. Too much water washes it away, but it takes more effort than the dry sand because water fills in the space between the grains enough to make the grains stick to each other. You will find that it takes a fan on higher settings to erode, or gradually wear away the sand.
Dry soil holds together better than dry sand. When it's wet, the organic matter and minerals fill the gaps in the soil to hold it tightly together. It takes a strong force (push) of water and wind to knock down a soil castle. This is why ancient Egyptians added straw to their mud when they made bricks for their homes. They molded the mud and straw, allowing them to dry in the sun, becoming bricks. Bricks are hard. Structures, like homes built today with bricks, are harder to tumble. Remember what happened in the Three Little Pigs?
Now that you've learned about sand and soil with this erosion experiment, keep the science going by testing more elements. Make this project more challenging by recording the time it takes for the structures to erode away with a stopwatch. What would happen if both wind and water hit the castles at the same time? What if you placed your hose at an angle or held it in the air and sprinkled in on your castles? Being a scientist is all about guessing and testing!
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.